2019 Email Benchmark and Engagement Study

Email statistics from senders and recipients

2019 Email Benchmark and Engagement Study

Chapter 1: Introduction

For the last 3 years, Twilio SendGrid has developed and published our Global Email Benchmark Report. In 2019, we’ve decided to take a different approach for this report. In addition to global email engagement benchmarks that we see from the sending side of things, we’ve also performed a study on the people receiving all those emails.

The 2019 Email Benchmark and Engagement Study is more impactful and useful than ever before. We continued our work with internal data scientists to provide engagement data that we see from senders, sending over 60 billion emails each month. Global benchmarks that we report on include:  

  • Aggregate Open Rate
  • Aggregate Click Rate
  • Click-to-Open Rate
  • Monthly Send Rate
  • Inbox providers and devices used in the top 25 countries by email volume

What’s inside this year’s report?

In addition to that, we performed an entirely new study focused on how recipients engage with email. Through this work, we’ve been able to answer a number of questions that are valuable to email senders, including:

  • How valuable is email to recipients?
  • How and why do people interact with marketing emails?
  • What compels people to open and click on certain emails over others?
  • How much email do recipients want to receive?
  • What are recipient frustrations and turn-offs?

Why is this report useful to me?

Like our reports in the past, this report can help senders make improvements to their current email program by learning about how email is being engaged with, where, and on what devices. By reading this report, you’ll be able to know a few different things:

  1. How effective your email program is by comparing your engagement statistics to the global averages.
  2. What devices and inbox providers are used in the top 25 countries we send email to.
  3. The key factors that influence why a recipient opens a message and clicks on links inside.
  4. What frustrates recipients about their inbox and about emails in general.
  5. How much content and what type of imagery you should include in your next email campaign.
  6. When recipients would like to tell you their email preferences.
  7. What makes an email stand out in the inbox.

A Focus on Something Other Than Industry Data

We coach our customers to listen to their recipients more than anything. Knowing that your industry’s average open rate is 5% doesn't mean much if the average open rate for your contact list is 15%. As a result, we’ve changed the focus of this report from previous reports, and are instead providing data on how recipients engage with the email they receive.

Chapter 2: Methodology and Data Collection for Global Email Benchmarks

This benchmark report contains metrics from email sent through Twilio SendGrid. These same metrics and methods have been applied in previous years and will be applied to future years and subsequent reports to consistently compare changes in email statistics and devices in different email regions.

The data for this analysis came from approximately 100 million recipient engagements from over 100,000 different senders. All data is anonymized and only analyzed/reported in the aggregate. 

This report is primarily representative of business to customer (B2C) email for the countries in which we have significant market penetration. 

This study may not be representative of personal email.

Twilio SendGrid collects metadata on all events in the email process, including delivery to the inbox provider, opening of email, and any clicks on links within emails. We use metadata to provide services and information to our customers and to improve our service as a whole. 

For the benefit of our customers and all email senders, we’ve summarized this data in the aggregate segmented by:

  1. Location of the recipient
  2. Device and inbox used by the recipient

Here’s how we analyzed and segmented our data:

Associating email with geography – IP addresses collected from opens and clicks were geolocated using up-to-date databases.

Detecting recipient devices – SendGrid uses user agent parsing libraries to automatically infer and categorize the hardware and software being used by a recipient when they open or click an email.

Determining recipient inbox provider – Recipient inboxes are inferred from the domain in the email address and from the IP address associated with the domain.

Chapter 3: Global Email Engagement Benchmarks for 2019

The global email benchmarks for 2019 are quite a bit different from what we saw in 2018, and they reverse a couple trends that were developing:

This data reiterates a lot of what we’ve coached senders on for years: as the number of messages to recipient inboxes increases, the engagement with those messages drops.

  • Aggregate Open Rate dropped from 18% to 14.5%
  • Aggregate Click Rate dropped from 2% to 1.6%
  • Click-to-Open Rate dropped from 11.1% to 10.9%
  • Average Monthly Send Rate increased from a median 7 emails per month to 8.3

As we can see, the average number of messages sent to recipients increased to 8.3 in 2019. This corresponds with the drops in Aggregate Open Rate, Aggregate Click Rate, and Click-to-Open Rate.   

An interesting note is that the Click-to-Open Rate continued to drop for the fourth year in a row. We believe that this demonstrates that recipients are increasingly selective about what messages they’ll interact with. While many recipients will open their emails, they’re not going to click on just any link within an email. 


Messages Could Be Getting Too Generalized

The drop in Click-to-Open rate could also signal that messages are too generalized. This is where larger, more sophisticated senders have the upper hand. Senders who are able to add more personalization have a better chance at getting those messages opened.

Table02 Mobile vs Nonmobile-1
Table02 Mobile vs Nonmobile-1

People will check email on almost any device they own. Whether they’re at work on a laptop, at home on their phone, or traveling with a tablet, people check their messages many times a day. It’s more important than ever before that your messages are able to load properly across all inbox providers, browsers, and devices. 

  • In 2019, the number of clicks on mobile vs. non-mobile increased from 55.6% to 61.9% on mobile devices. This could be attributed to changes in industry volumes. For instance, there are a lot of political emails being sent right now, more than in non-election years. People could be interacting with this increased political sending on their devices rather than their computers, causing an uptick in mobile usage.
  • This may seem counterintuitive, but recipients in our study said they not only switch between mobile and non-mobile devices, they even prefer to look at some messages on desktop over mobile because it’s easier to click links and search for things with the keyboard.
Top 3 Inbox Providers in Top 25 Countries
Top 3 Inbox Providers in Top 25 Countries

This table shows the percentage of recipients that have that type of inbox provider in each country, not the volume of email each inbox provider receives in each country. Each recipient gets counted once per email address. If a person has one account, regardless of how many messages go to that account, they’re only counted once.

  • Gmail continues to be the inbox used by most people across most countries, with Yahoo and Hotmail generally in second or third place. Each of these inbox providers require properly authenticated email in order for it to be delivered correctly. Make sure your IP address and domain are authenticated to ensure your email is being placed where it should be.
  • Outside of the top 3 inbox providers, senders should be aware of the smaller providers in countries they send email to as these could represent a significant number of customers or users. 
  • Usage of the top three inbox providers dropped slightly in the United States, which indicates that other, smaller providers are gaining some usage.
  • While Gmail has the largest share of email addresses in Germany, it still only accounts for 20.8% of all addresses in that country. This is a situation where senders should be aware of the inbox providers their recipients use. If you have a lot of German recipients on your list, you may be sending email to 6 different inbox providers, so you’ll want to make sure your account is authenticated and your messages load correctly across all of them.  
  • Other countries, like Russia, have Gmail as well as 2 other inbox providers (mail.ru and yandex.ru) that we don’t see in any other countries. This could be attributed to Russia using the Cyrillic alphabet as opposed to the Latin alphabet used in most other countries.
Top 3 Inbox Providers in Top 25 Countries
Top 3 Inbox Providers in Top 25 Countries

Twilio SendGrid uses user agent parsing libraries to automatically infer and categorize the hardware and software being used by a recipient when they open or click an email. In the table above, a “generic” device is typically something that is running on the Android operating system, but has masked the type of device used. These mobile devices could be a combination of any number of device manufacturers like Huawei, LG, Google, OnePlus, Motorola, etc.  

  • In general, senders should make sure their messages load properly on all Samsung, Apple, and other Android devices. These are the operating systems most commonly used across the world.
  • Apple’s share of devices actually dropped in a handful of countries, including India, Indonesia, and Argentina. If you’re sending international email to these locations, make sure your mail is loading well on Android devices. 

Look at Engagement at the Device Level

Consider looking at your click rate at the device level. If you see that there's a strong click rate on Android devices, but there's a drop-off when it comes to iPads, it could point to emails not working correctly on those devices and/or operating system. We've met with some customers who haven't re-worked their emails in years, and as a result, they don't work with the updated software.

Chapter 4: Recipient Email Engagement Data and Insights

While it’s helpful to know what the email engagement benchmarks are as a sender, there’s an equally important aspect of the email communication channel: the recipient. This year, we set out to answer some fundamental questions around recipient engagement:

  • What emails are recipients interested in engaging with?
  • What elements impact a recipient’s choice to open and click on an email?
  • When do recipients become frustrated with the number of emails they receive?
  • Why do recipients ultimately decide to unsubscribe?
  • What email elements stand out to recipients most?
  • What makes an email memorable to recipients?

By listening to recipients and learning about what they’d like to see in their inboxes, senders can craft and send more valuable emails that have a better chance of being opened and engaged with.

Chapter 5: Methodology and Data Collection for Recipient Engagement

The recipient engagement portion of this report was conducted with a qualitative ethnographic study, and a quantitative online survey, both of which were conducted in the United States (U.S.) and the United Kingdom (U.K.). 

Qualitative email insights

To gain qualitative email insights and to track daily email usage habits, we interviewed 40 total study participants, with 20 in the U.S. and 20 in the U.K. The sample was segmented by age group, divided into the following age brackets:

  • Gen Z: 18-24, 5 in the U.S. and 5 in the U.K
  • Millennials: 25-35, 5 in the U.S. and 5 in the U.K
  • Gen X: 36-50, 5 in the U.S. and 5 in the U.K
  • Baby Boomers: 51-60, 5 in the U.S. and 5 in the U.K
Graphic depiction of how study participants were segmented
Graphic depiction of how study participants were segmented

The participants used a mobile ethnography app to answer email-related questions throughout the day. They were sent 3-5 questions a day for 5 days. Using video responses (approximately 1-2 mins in length), along with screenshots and phone-screen recordings, participants shared with us their daily email habits. This gave us more detailed feedback than an interview alone, as it allowed us to observe and track over time.

At the conclusion of the week, we debriefed with participants in an in-depth video interview lasting 30-45 minutes.

Quantitative online survey

Once we completed the mobile ethnographic study, we wanted to quantify those qualitative themes, and see if these findings applied across a statistically valid sample size. We developed an online study that was conducted in the U.S. and the U.K. with 800 participants from each. Those participants were then divided up amongst the 4 different age categories so that 200 participants in each category completed the survey.

Chapter 6: Email is Essential

Throughout all our research, one thing was reiterated over and over again: email is not only important, it’s an essential channel for communication between recipients and companies. Most of our study participants say the emails they receive from businesses are valued because they provide important information that they want.

Emails help people track what they’ve bought online, when orders will ship, alert them to sales and discounts, remind them what bills they have to pay, and provide updates about the brands they love. Email has become a part of their morning rituals and routines. Some even say they’re addicted to their email.

Across the U.S. and the U.K., and across all age groups, 84% of participants check their email at least once a day, with the majority of people checking messages numerous times throughout the day.

Email is ingrained in everyday life for almost everyone. We found that across all study participants, email was the most essential communication channel. 97% of study participants consider email to be essential, followed by text messages, and then social media.

“I periodically check it through the day when I’m working, or just whenever I have time during my day.”

U.S. Millennial
bar chart of what communication medium is essential to your life?
bar chart of what communication medium is essential to your life?

Email isn’t going anywhere. Participants in the study not only use email on a daily basis, they want to receive communications from companies via email messages. Email is the expected channel for promotional content from businesses they interact with.

“I check my emails in the morning and while commuting to work on public transportation. I check emails throughout the day to see if there's anything that requires an immediate response. In the evening, I will go through emails using my laptop as it's quicker to type with a keyboard.”

U.S. Baby Boomer

Target Your Messages as Much as Possible

With so many messages going to recipient inboxes, and with recipients checking their email multiple times a day, as a marketer, you should be thinking about how you can make your email as targeted and personalized as possible.

Chapter 7: Email Frequency

We saw in Twilio SendGrid’s email benchmarks that the average number of emails sent each month to recipients increased from 7 in 2018 to 8.3 in 2019. We wanted to learn more about how comfortable recipients are with the amount of email they receive and the frequency of messages they get from companies they’re interested in.

Pie chart of How Frequently Do You Like to Receive Emails From a Company with Products That Interest You?
Pie chart of How Frequently Do You Like to Receive Emails From a Company with Products That Interest You?

Based on these results and our qualitative study, recipients are more forgiving when emails are sent by one of their favorite retailers. They’re even open to the idea of receiving daily messages, just as long as they want the product or service offered, or they’re particularly interested in the sender or brand. 

For the most part though, receiving too many messages in a short span of time often results in a quick deletion, and can trigger an unsubscribe with repeat offenders.

Most of our study participants said they would only like to receive promotional emails from retailers once a week, and just a few say they are fine with daily emails. A few others are open to seeing emails outside of this frequency if a limited time offer is involved.


Identify Your High Volume Recipients

Email senders should identify which recipients want to receive email once a day, and which want to receive email once a week. Once you have an idea of who wants to receive a lot of email and who doesn't, you should think about your offers. Do your offers necessitate a once per day email? Are you sending different offers each day, or are you sending the same thing over and over again?

Get Email Inspiration


Content Calendar 2020 Social Assets Blog 2430x1000
Content Calendar 2020 Social Assets Blog 2430x1000

Chapter 8: Elements of a Good, Successful Email

If you were asked right now, what were the last 10 emails you opened, would you be able to name them? Chances are, you might be able to describe a couple, but not much more than that. There’s more email being sent today than at any other time in history, which is why making an email memorable and interesting to recipients is so important. 

We wanted to learn more about what makes a good, successful email stand out from the rest. So we asked our study participants to provide us with their insights and opinions around a number of different email elements, including:

  • Personalization
  • Images, Videos, and GIFs
  • Content
  • Responsiveness

Below, we’ll dive into each of these topics with the relevant quantitative analysis and any relatable insights from our mobile ethnography.


These days, some level of personalization is expected in essentially every email that comes to the inbox. Whether you’re including a recipient’s name, including specific information exclusively for them, or just sending them product offers, recipients expect senders to know something about them.

Bar chart of How Influential is Personalization on Making an Email Memorable?
Bar chart of How Influential is Personalization on Making an Email Memorable?

Across both the U.S. and the U.K., 26% of study participants said that personalization is something that would make an email very memorable. Another 38% of participants said that personalization would make the email somewhat memorable.

“Companies can sort of hone in on your likes or products that you tend to get so they can tailor what they're sending you.”

U.K. Gen X
bar chart of U.S./U.K. split of How Influential is Personalization on Making an Email Memorable?
bar chart of U.S./U.K. split of How Influential is Personalization on Making an Email Memorable?

When we compare the U.S. and the U.K. next to each other, we see that responses were very similar. 29% of those in the U.S. said that personalization was something that made an email very memorable, compared to 22% in the U.K.

In interviews and in our mobile ethnography, many recipients suggested they would be more inclined to read emails they receive (and not delete or unsubscribe from them) if they were more personalized or relevant. Recipients like seeing emails that include their name because it suggests the content is exclusively for them.

“I like it when they use my name and put something in there that is more than just some sort of automated thing.”

U.S. Baby Boomer

Personalization Doesn't Mean Adding a First Name

Personalization no longer means adding a first name or a location to an email, those things are expected. Real personalization means providing content and offers specific to the recipient and their past actions or purchases.

Images, videos, and GIFs

Imagery is an essential element of just about every email. Whether you’re including pictures of your products, a background image in your brand’s colors, a GIF highlighting new features, or a video walkthrough of your software, images help you convey your message. We wanted to learn what the right number of images is for an email from the recipient perspective.

Pie chart of Ideal Number of Images in an Email
Pie chart of Ideal Number of Images in an Email

Overall, recipients want images in their emails, but they only want a few at most. The vast majority of participants, 85% across the U.S. and the U.K., indicated they’d like 1 to 3 images in their emails at most.

Bar chart of U.S./U.K. split of Ideal Number of Images in an Email
Bar chart of U.S./U.K. split of Ideal Number of Images in an Email

Looking at the four age groups across both the U.S. and the U.K., we see that for the most part, people want to see one, two, or three images in an email. Very few participants wanted no images, and even fewer participants wanted five or more images in an email.

“I like a lot of pictures in my emails. If I just get a bunch of words and everything in the email was just typed, I don't want to have to read through that. I prefer emails that have lots of pictures but get the point across and give me the information I need.”

U.S. Gen Z

Through our interviews and mobile ethnography, our participants told us a few additional things about what they think about images in email:

  • Images add more context to the messages they receive.
  • Images and video content should load quickly and display properly, especially on mobile devices, otherwise they detract from the message.
  • Recipients are especially fond of images that help illustrate products and services, like clothes or travel destinations, and videos that demonstrate how a product might be used or assembled.
  • Some recipients are open to emails that are more interactive and use more images/graphics. There’s also some interest in seeing more video, which a few felt would be quite novel.
  • Most recipients expect to see less text when images are present, or a better balance of text and graphics.
  • Most recipients do not want emails to have too many images, which can make them look busy.

To learn more about their opinion of GIFs and video in email, we asked them if they liked GIFs and video in email from companies advertising products or services. 

Pie charts of Do You Like GIFs or Videos in Emails from Companies Trying to Advertise Products or Services? Pie charts of Do You Like GIFs or Videos in Emails from Companies Trying to Advertise Products or Services?

Across all age groups and locations, the majority of people do not like GIFs or videos in their emails. The most tolerant age group across the two countries were Millennials, with 51% saying they did not like GIFs and video. The most intolerant of the age groups were Baby Boomers, with 76% saying they didn’t like GIFs and video.

When we looked at the data more granularly, to see the age groups within countries, there were some other interesting takeaways.


Lots of Images Mean Slower Loading Times

Think about the bandwidth your recipients may or may not have. Every image you include in an email means that it'll take longer to load and increase the chances of an image breaking, which leads to a poor recipient experience.

Bar chart of Do You Like GIFs or Videos in Emails from Companies Trying to Advertise Products or Services? Bar chart of Do You Like GIFs or Videos in Emails from Companies Trying to Advertise Products or Services?

When age groups are split by country, we see that there are some where the majority of participants actually like GIFs and video. Millennials and Gen Z participants in the U.S. both indicated they like these moving images with 56% responding with “yes.” 

Another interesting note is that U.S. participants were much more tolerant of GIFs and videos than those in the U.K.. The group that indicated they absolutely do not like GIFs and videos are Baby Boomers in the U.K.. Some qualitative insights we got about GIFs and video include:

  • Images can be animated, but should not endlessly strobe or blink.
  • A few older participants were a little leery about receiving video or clicking links to see video because they could lead to viruses.


The content within an email is just as important as every other email element. An email with a great subject line and no content doesn’t provide the recipient with any useful information. Email content should be descriptive and provide your recipients with information about the offer you’re sending, or tell them why they should engage with the links in the message. Like images, having too little content or too much are both turn-offs for recipients:

Much like their criticism of subject lines, study participants really dislike emails that are too long and wordy, and not very concise. However, an email with no content, and just images is also not interesting to recipients. The general consensus is that an email should definitely have some content, just not too much. Other qualitative takeaways include:

  • Some emails can be difficult to read if they are too text-heavy. 
  • Recipients are turned off when emails have spelling errors, which suggests a lack of professionalism.
  • Some prefer shorter emails, which only require a quick scroll or two to read, and want these every other day. 
  • Others say they prefer longer, more detailed emails, particularly if they are interesting and relevant, but would only want to see these once a week or less.
  • Recipients dislike it when the content of an email doesn’t live up to the subject line that enticed them to open. 
  • A few also dislike emails that take a hard sell approach, seem too pushy, or try to guilt them into buying something.

“If it becomes too long, then you're not going to read it, unless it's obviously some sort of whitepaper or something that you want to read. But if it's something that's just out there just to grab your attention, it should be just scrollable very quickly.”

U.K. Baby Boomer


Email recipients expect an email to load properly on the device they’re using to view it. Whether it’s a phone, tablet, or computer, your email should appear correctly so that they don’t have to zoom in or scroll awkwardly in order to read it.

Of all participants, 66% said that it is essential for an email to load properly on all devices. In the U.S., this percentage grows to 70% of participants, and drops to 63% among U.K. participants. 

Study participants specifically told us that they would like it if senders formatted their emails so that they display properly on different devices, and take into account the narrowness of phones versus the wider displays they have on their computers and laptops.

“I'm checking email on my phone a lot, so if it doesn't fit, and if it's not sized correctly for my phone, I'll probably delete it.”

U.S. Baby Boomer

We also wanted to learn more about how often email recipients open an email on one device, and then switch to another.

Bar chart of How Often Do You Open Messages on a Phone and Then Switch to a Computer and Vice Versa? Bar chart of How Often Do You Open Messages on a Phone and Then Switch to a Computer and Vice Versa?

A quarter of respondents said they “never” switch between their phone and computer, while about 60% said they seldom or sometimes switch between the two. Recipients may not switch between devices a lot, but when they do, the email should load properly. 

We saw in our qualitative study that recipients may not go from one to the other very often, but sometimes it makes sense to switch to a computer. If recipients see an offer or promotion that looks particularly enticing on their phone, some will switch to their computer to take advantage of it and complete their transaction.

Country breakdown of How Often Do You Open Messages on a Phone and Then Switch to a Computer and Vice Versa? Country breakdown of How Often Do You Open Messages on a Phone and Then Switch to a Computer and Vice Versa?

Based on our study, the group of people who said they switch between devices the most were Gen X participants in both the U.S. and the U.K. 11% said they frequently switch between devices, and 43% of Gen Z recipients in the U.K. said they sometimes switch between the two. 

What’s interesting here is that it is the younger age groups that say they’re switching from their phone to the computer and vice versa. 35% of Baby Boomers said they never switch between the two, while only 20% of Gen Z, 22% of Millennials, and 28% of Gen X participants said they never switch. Millennials had the highest percentage of sometimes switching at 38%.


Responsive Design is More Than Just Responsive Layout

Responsive design doesn't just mean ensuring your email loads and displays properly across devices, it means ensuring your calls-to-action are relevant across platforms. If you're sending an email that has a link that opens an app on a phone, the experience may be broken if the recipient is clicking that link on their desktop. The link on the desktop should go to a landing page that describes the feature in more detail, encouraging the recipients to go back to their phone and engage with the app.

Chapter 9: Factors That Influence Opening an Email

We saw in Twilio SendGrid’s email engagement benchmarks that the aggregate open rate for email dropped this year to 14.5% while the number of emails sent by all senders increased in frequency. For recipients, this means they’re getting a lot of email in their inboxes, and they have to decide what they want to open.  

We asked participants in both the mobile ethnography and the online survey to rank the elements of an email that impacted their decision to open the message:

  • Sender
  • Subject line
  • Offer/promotion
  • Content
  • Time of day
Bar chart of Factors That Determine Whether or Not to Open an Email Bar chart of Factors That Determine Whether or Not to Open an Email

Overall, the most important element of an email that impacts a recipient’s choice of whether they should open it or not, is the sender. Recipients typically check who an email is coming from before choosing to read the subject line or determining what’s inside the email itself.


The sender instantly conveys where an email is coming from. Emails are more likely to be opened when recipients have some relationship with that company, or are expecting to receive emails from these trusted, subscribed-to sources.

Bar chart Influence of Sender on Opening Email Bar chart Influence of Sender on Opening Email

The chart above shows that across all ages in the survey, more than half of respondents said that the sender would strongly influence their decision to open an email. That influence is strongest with the Baby Boomer group, with 61% saying that the sender is a strong influence. The Gen X group had the lowest number of people saying the sender is a strong influence, at only 45%.

“Who the email came from is most important to me. If the subject captures my interest, then that is second. If the sales offer or discount appears to be good, I will open it.”

U.S. Baby Boomer

Opening an Email is Like Opening the Door to Your Home

You can think of opening an email like opening the door to your house. If you look out the peephole and see someone you know, you're a lot more likely to open the door, as opposed to just seeing a stranger holding a box.

For some recipients, the sender alone is all the information they need to open an email, especially when they are very fond of a particular brand. In general, when recipients open their inbox, the sender is the first thing they look at, and if they don’t feel like seeing that company’s product or service, they scroll right past.

Another interesting thing is that the sender remains the most influential factor for opening an email across the U.S. and U.K. as well. Below are charts comparing how the sender influenced study participants in the U.S. and the U.K. The results are very similar:

Bar chart of country split of Influence of Sender on Opening Email Bar chart of country split of Influence of Sender on Opening Email

The bottom line is that your emails are much more likely to be opened if the recipient knows who you are and is interested in your company or brand. Messages getting sent to recipients who are unaware of you, or who have never interacted with you in the past, are going to be ignored.


Friendly Froms

Recently, political senders have been employing the use of “friendly from” addresses in their emails. Friendly from addresses are the visible part of an email address displayed in email clients as the person/entity sending the message. For instance, the email address might include a familiar name like “Britney.Spears” and @yourdomain.com. This tactic may seem like a good way to stand out in the inbox, but in reality, if it confuses recipients, it may be ignored or even flagged as spam.

Subject line

Recipients want to have a clear idea of what an email is all about before they even open it, which is where subject lines come in. However, recipients didn’t indicate that subject lines have more influence over their decision to open than who the email is coming from:

Bar chart of Influence of Subject Line on Opening Email Bar chart of Influence of Subject Line on Opening Email

Unlike with the sender of an email, participants were a little more unsure of how influential an email’s subject line is on their decision. Most study participants were split between a subject line strongly influencing the decision, or just somewhat influencing the decision. This split is reflected across the U.S. and U.K., too:

Bar chart of Influence of Subject Line on Opening Email Bar chart of Influence of Subject Line on Opening Email

Subject lines should be clear and concise, and descriptive enough so they are not vague and ambiguous. Participants said they liked subject lines that were interesting and informative, have a hook, or present information in a fun and catchy way because they’re more compelling.

“The subject line is most likely to draw me in and I'll notice that before anything else.”

U.K. Gen Z
Table of subject line dos and don'ts
Table of subject line dos and don'ts

“Something that summarizes the content is good. If it's ambiguous, I really don't connect. I just feel like it's click bait.”

U.K. Gen Z


The content of an email is an extension of the subject line and sender. Typically, the purpose of the subject line is to describe the content of the email itself and encourage the recipient to open the message, but the best subject line ever written won’t help if the content of the message isn’t relevant or interesting. One really doesn’t work without the other.

Bar chart of Influence of Content on Opening Email Bar chart of Influence of Content on Opening Email

What’s inside the message is the second most influential factor when it comes to the open decision, and this data reflects what we heard from our mobile ethnography participants:

  • Relevant content is valued, but content must also echo the subject line—recipients don’t want to be disappointed, or feel their time was wasted after opening an email. 
  • Some recipients say content is moot—they won’t read it if they don’t get past the sender or subject line.

For senders, this means that the sender, subject line, and content are all working together pretty closely. A recipient wants a clear descriptive subject line that tells them about the value inside the email, from a sender they recognize and like. This influence was reflected across both countries as well, with the U.S. ranking content as having slightly more influence than the U.K.

Bar chart of country split of Influence of Content on Opening Email Bar chart of country split of Influence of Content on Opening Email

Offers and promotions 

For many ecommerce businesses, the subject line is really just a way to inform recipients about their current offers and promotions. You’ll notice plenty of these in your inbox right now:

  • Save $50 by Ordering Now!
  • Reminder: 50% off your delivery fee
  • Take an extra $15 off your next order

A lot of study participants will scan their inbox for large discounts, verify the sender, and then choose to open the email itself.

Bar chart of Influence of Offer and Promotions on Opening Email Bar chart of Influence of Offer and Promotions on Opening Email

Interestingly, the influence of the offer or promotion was ranked differently between the U.S. and the U.K.:

Bar chart of country split of Influence of Offer and Promotions on Opening Email Bar chart of country split of Influence of Offer and Promotions on Opening Email

U.S. participants seem to indicate that the offer or promotion is more influential to them than their peers across the pond. In the United Kingdom, participants leaned more toward offers and promotions having “somewhat” of an influence on their choice. 

Our qualitative study participants told us that deep discounts, sales, and promotions often catch their eye, particularly when these are touted in the subject line, but what’s sold must align with what they need. Several recipients said they wouldn’t bother opening an email unless they received at least 40% off.

“If it's a quick thing, I might read it and then keep it in my inbox before deleting it. Unless it says act fast now and get 50% off this item, I'll probably just let it sit there.”

U.S. Millennial

Add Variety to Your Offerrs

Recipients are skeptical of receiving the same coupon week in and week out. When each of your emails provide recipients with 20% off a purchase, they no longer stand out in the inbox.

Time of day received

As we showed previously, the vast majority of email recipients are checking their email multiple times each day. This means that the time of day that they receive an email isn’t as important as it may have been in the past. While you want to make sure your email reaches people, and stays toward the top of the inbox, most recipients are going to check their messages to see if they’ve received anything recently.

Bar chart of Influence of Time of Day on Opening Email Bar chart of Influence of Time of Day on Opening Email

Of all the email factors, time of day was ranked as having the least influence on the decision to open an email. On average, only 13% of all participants indicated that time of day had a strong influence on their decision. This was also reflected across both countries:

Bar chart of country split of Influence of Time of Day on Opening Email Bar chart of country split of Influence of Time of Day on Opening Email

During our mobile ethnography study, our participants echoed these quantitative results. Participants said that time is of little importance, as they check email throughout the day, and they will open a good email regardless of when it is received. The only time they said that time of day was important was when the message was time sensitive.

“Time of day received is my least important. I don't care what time of day I receive an email unless it's very important...”

U.S. Gen X

As you continue along the recipient’s engagement journey, after they choose to open an email, they’re brought to another decision: what should I click on in this email? Over the last 4 years, the average click-to-open rate has dropped from 13.6% in 2016 to 10.9% in 2019. This suggests that recipients are opening messages quite a bit, but they’ve become more selective on the offers they’ll actually click on within messages.

In order to learn more about the decision to click on links within emails, we asked study participants to rank how influential each of the following factors would be in prompting them to click on a link:

  • Critical information (shipping notification, receipt, password link, etc.)
  • Relevant products
  • Offer/discount
  • Link placement
  • Color of link
  • Link copy
  • Brand of sender
  • Content of email
Bar chart of Factors That Influence Whether or Not to Click Links Within an Email Bar chart of Factors That Influence Whether or Not to Click Links Within an Email

Unlike the decision to open an email, there isn’t one factor that clearly influences the decision to click links more than others. Across all study participants, the email factors with the highest percentages of respondents saying they would strongly influence their decision, include: 

  • Offers/discount
  • Critical information (shipping notification, receipt, password link, etc.)
  • Content of email
  • Relevant products
  • Brand of sender

These factors also had the lowest percentages of recipients saying they wouldn’t influence their decision very much or at all. The other email factors (link color, link copy, and link placement) don’t seem to have nearly as much influence on the choice to click on an email. When we looked at how the U.S. and the U.K. ranked these factors, some interesting differences arose:

Bar chart of Factors That Influence Whether or Not to Click Links Within an Email in the United States Bar chart of Factors That Influence Whether or Not to Click Links Within an Email in the United States
Bar chart of Factors That Influence Whether or Not to Click Links Within an Email in the United Kingdom Bar chart of Factors That Influence Whether or Not to Click Links Within an Email in the United Kingdom

Unlike the U.S., participants in the U.K. ranked factors as having a strong influence much less than the participants in the U.S. For instance, when it comes to critical information in emails, only 29% of U.K. participants said that factor had a strong influence, as opposed to 43% of U.S. participants.  


The offer/discount within an email had the highest percentage of people who considered it to have a “strong influence” on their decision to click on a link at 39%. 

Bar chart of Influence of Offer/Discount on Clicking Links Bar chart of Influence of Offer/Discount on Clicking Links

These rankings reflect what we learned earlier about why participants choose to open an email. If an email is touting a deep discount in the subject line, the recipient may choose to open the message itself, and in order to capitalize on the discount, they’ll have to click on a link to the site. 

Other emails may be very informative and get opened, but they don’t necessarily require a click on a link. A newsletter or welcome email is a good example of an email where a recipient might open the message, but not necessarily click on any of the links. 

Content of email

While some promotional emails are very straightforward, others require some content in order to drive value and influence recipients to take the next step by clicking on a link. The content of an email had the second most rankings of “strong influence” at 37%.

Bar chart of Influence of Content on Clicking Links Bar chart of Influence of Content on Clicking Links

This is good news to any email marketer out there spending time crafting good, informative email content because it shows people are actually reading and evaluating what you’re sending them. As a sender, you should try to send your recipients messages that provide value. Not every email campaign can be a 50% off promotion.

Critical information

Critical information in an email can be many different things, but generally, it’s information that’s included in transactional emails:

  • Shipping notifications
  • Receipts
  • Purchase confirmations
  • Password reset links

We looked at these types of emails and what they provide as different from the more general “content” email factor.

Bar chart of Influence of Critical Information on Clicking Links Bar chart of Influence of Critical Information on Clicking Links

Study participants were split on how much of an influence critical information has on their decision to click links with 36% saying it would have a strong influence, and 34% saying it would have somewhat of an influence. Millennials had the highest percentage of participants saying it would have a strong influence at 41%.

For something like a password reset email, the whole purpose of the message is to provide you with the link inside the email. For others, like a purchase confirmation, a recipient will most likely open and look at the message, but they probably won’t click on anything inside, unless something looks wrong.

Relevant products

Recipients view emails from brands they like, with information about products they want, to be more than just promotional emails. Study participants told us emails that are informative and functional get attention and are useful. They believe emails about new product announcements and upcoming sales, especially when they include coupons, fall into this category.

Bar chart of Influence of Relevant Products on Clicking Links Bar chart of Influence of Relevant Products on Clicking Links

Fewer participants ranked relevant products as having a strong influence at 32%, and 41% said it had somewhat of an influence. 

Our qualitative study participants told us that once they choose to open an email, if it’s from a retailer or other ecommerce site, they want to see relevant products. However, we’ve already seen that the Click-to-Open Rate has been dropping for the last 3 years, which means, they may want to see these items, but they’re going to be even more selective in clicking on things. Recipients want:

  • Emails to reflect the buying history they have with the vendors and retailers they subscribe to. 
  • To receive offers and discounts for items similar to the ones they have bought in the past, and not for items they might have only been browsing on a company’s website.
  • News about the products they currently own, and whether upgrades or new versions are available.
  • Curated recommendations based on their previous activity. Recipients expect retailers to anticipate their needs and suggest goods they should be buying.

Don't Do Too Much With Your Email

Rather than attempting to include all your value props and story in an email, senders should focus on driving recipients back to their website. Once a recipient has come to your website, you have a lot more control over their experience, the offers and products they see, and how they finally purchase something.

Brand of sender

Much like how the sender strongly influences the decision to open an email, the brand of the sender also has an influence on the recipients’ choice to click links within an email. Many recipients will see who’s sent them an email, open the message, and even if they don’t see anything in the message they like, they’ll click through to the site because they have an affinity for that brand and their products.

Bar chart of Influence of Brand of Sender on Clicking Links Bar chart of Influence of Brand of Sender on Clicking Links

In addition to being one of the influencing factors in deciding to click email links, the brand of the sender can also cause frustration. Recipients particularly dislike when these emails do not come from a recognized sender. When that occurs, the emails seem suspicious and dishonest. This makes them feel like they are getting spam.

As an email sender, make sure you’re following address collection best practices so that your messages are only being sent to recipients who are familiar with your brand, and want to receive those messages.

Link placement, link copy, and color of link

Many senders spend a lot of energy thinking about how they can make the links in their email stand out, and we’ve all heard stories about changing the color of a button in order to drive more clicks. Unfortunately, the color, placement, and even the text of the link are all factors that recipients say have the least amount of influence.

Bar chart of Influence of Link Placement, Copy, and Color on Clicking Links Bar chart of Influence of Link Placement, Copy, and Color on Clicking Links

Obviously, links are critical for any email, but rather than focusing on the perfect color of a button or call to action, senders should focus more on providing value in their messages, and having a call to action that stands out, that recipients can engage with.  

Chapter 11: What Drives Email Frustrations and Unsubscribes?

While it’s nice to know what recipients prefer or enjoy about email messages, it’s equally important to understand what frustrates recipients about the email experience. Identifying these frustrations can help email senders improve their emails and sending habits so that recipients are more likely to engage with their emails, and less likely to unsubscribe. 

Below, we look at a few different parts of the recipients’ email experience. We asked our study participants 3 questions:

  • What do you find frustrating about your inbox?
  • What are the top turn-off factors in email?
  • What frequency of emails would prompt you to unsubscribe from an email distribution list from a company with products that interest you?

Inbox Frustrations

Just about everyone has some type of email inbox. In 2018, The Radicati Group, Inc. estimated there were about 3.8 billion email users around the world, and that number is expected to grow to more than 4.2 billion by 2022. 

Whether they’re checking it multiple times a day, or just once every day or two, they have a repository of email messages. The email experience can be frustrating for recipients, especially with the volume of email each person is receiving. We asked study participants to rank the following frustrations about the inbox for us:

  • Number of messages
  • Unknown senders
  • SPAM filters not accurate
  • Hard to search for emails
  • Too hard to unsubscribe from emails from companies
  • Emails that aren’t designed for mobile devices and don’t load properly
  • Difficult to organize for relevant emails from senders I want to receive email from
  • Other (Fill in)
Bar chart of What Do You Find Frustrating About Your Personal Email Inbox? Bar chart of What Do You Find Frustrating About Your Personal Email Inbox?

Across all age groups, the three factors that recipients found to be most frustrating were:

  • Number of messages
  • Unknown senders
  • SPAM filters not accurate

This means that recipients are tired of getting so many emails in their inbox, especially from unknown senders. “Spam filters not accurate” indicates that recipients are frustrated when wanted email is sent to SPAM incorrectly. These three frustrations remain in the top when we look at age groups in both countries.

Bar chart of What Do You Find Frustrating About Your Personal Email Inbox? by country Bar chart of What Do You Find Frustrating About Your Personal Email Inbox? by country

One interesting difference between the two countries is that unknown senders seem to be what frustrates people the most across all age groups in the U.K. at 56%. In the U.S., the three top frustrations are much closer. As a sender, this reiterates what we tell our customers: make sure you’re only sending email to people who are familiar with your brand and want to receive your messages.

The top turn-off factors in email

Now that we know what’s frustrating recipients about their inboxes in general, we decided to dive a little deeper and learn about what frustrates them about the messages they receive and open. We asked study participants to choose their top three email turnoffs from the following list:

  • Irrelevance
  • Emojis
  • Grammatical/spelling errors
  • Unknown brand or company
  • Un-personalized content
  • Poorly Designed graphics/text layout
Bar chart of Top Three Email Turn-Offs Bar chart of Top Three Email Turn-Offs

By far, the three biggest turn-offs for our study participants were:

  • Irrelevance
  • Unknown brand or company
  • Grammatical/spelling errors

Email recipients dislike irrelevant messages. For instance, sending an email about dog chew toys to cat owners will likely frustrate the recipient far more than drive engagement. Second to irrelevance is email from unknown brands or companies. Mail from unknown senders isn’t likely to be opened, and it adds to the rest of the messages in inboxes. 

Lastly, grammar/spelling errors in emails is frustrating to recipients because it makes the message look suspect, and makes the brand look unprofessional. Make sure you’re always double-checking your messages so they’re typo-free!

Bar chart of Top Three Email Turn-Offs by country Bar chart of Top Three Email Turn-Offs by country

Looking at differences between age groups and locations, Baby Boomers appear to be the most intolerant of irrelevant emails, with 84% in both countries ranking that as the biggest turn-off.


Your Recipients Know What They're Looking For

Email has been around for so long now, and recipients are so familiar with it, that they know what email should and should not look like. By pushing the boundaries and incorporating any and all new graphic design trends, you could be turning your recipients off instead of intriguing them.

Emojis: 🥰 or 😫?

Emojis didn’t rank very high in our quantitative survey, which could mean they still turn people off, just not as much as the top three. Our qualitative study participants, however, definitely had some opinions about them. 

Of all the age groups, Gen X and Baby Boomers dislike seeing emojis the most, and suggest they’re annoying. They feel emojis are unprofessional, look childish, and often cheapen an email offering. This is especially true if the sender is a financial institution or one where trust is a cornerstone of a business relationship.

GenZ and Millennials tend to be more split when it comes to emojis. While several echo what the older generations say, some feel emojis do fit with certain brands that are fun and playful. 

The bottom line is, as a sender, you should have a good read on your recipients and customers. If your customers tend to be a bit older, it may be worth skipping emojis in your subject lines. If you’re a younger company with a young client base, include them, but don’t go overboard.

What frequency of emails would prompt an unsubscribe

As we saw above in our global benchmarks, the average number of messages sent each month increased in 2019 from 7 to 8.3 messages per month. This means that on average, email senders are messaging their recipients more than twice each week. 

We wanted to learn if an increase in sending frequency would cause recipients to unsubscribe from an email list.

Bar chart of What frequency of emails would prompt you to unsubscribe from an email distribution list from a company with products that interest you? Bar chart of What frequency of emails would prompt you to unsubscribe from an email distribution list from a company with products that interest you?

What’s interesting to note, 54% of all participants say that if a company were to increase their sending frequency to an email every day, it would be a significant factor in their choice to unsubscribe from that email list. 

Receiving too many emails from the same sender over the course of a week is one of the biggest pet peeves reported  in our recipient ethnography study. Their annoyance is compounded when a company bombards their inbox multiple times a day, or the offers they receive are all very similar, and the sender does not seem to have anything new to say.


Have a Relationship With Your Recipients

Have a closer relationship with your recipients and know what they've bought in the past. If you have someone that bought a product they won't need to replace for a year or two, continuing to send them offers on that same product isn't going to drive another purchase. Think about other products they may want or need.

“Receiving an email every day is a nuisance...certainly every other day probably as well.”

U.K. Millennial

While they say they appreciate emails that might benefit them in some way, such as those that promote a sales event or offer a discount for an online purchase, several say promotional emails can also be quite annoying.

Frequency was also important to several participants who were turned off when companies send too many emails in a short span of time, or when these emails look too similar and feel too repetitive.

“I would say not more than once a week, and I think once a week is pushing it.”

U.S. Gen Z

Email preferences

In general, the best way for an email sender to get recipients to open and engage with emails is to send them content and offers they want to receive. We’ve already seen that irrelevance is one of the most frustrating things about emails, so ensuring those emails are relevant to recipients should be at the top of the list for email senders to do.

One of the easiest ways to accomplish this is to simply ask recipients what type of email they’d like to receive. Oftentimes, companies only provide an email preference center when a recipient has decided to unsubscribe from their messages. Unfortunately, this isn’t when recipients want to give you their email preferences.

Overall, 60% of participants would prefer to tell companies exactly what kinds of email they’re interested in right when they provide their email address for the first time. An additional 24% of respondents said they’d be interested in a survey emailed to them soon after providing their address. 

When we look at how these responses compare country to country, there are a couple of interesting things observed:

Bar chart of When do you want to tell companies what type of emails you want to receive? by country Bar chart of When do you want to tell companies what type of emails you want to receive? by country

While the vast majority of participants still want to provide their email preferences when they first submit their email address, 13% of Baby Boomers across both countries said that they don’t want to share their email preferences.

“I wouldn't mind filling in a survey or a form online. I think it feels less creepy if it's done via a survey.”

U.K. Gen Z

For the most part, companies are eager to gain new email subscribers, but they’re not as interested in letting the subscriber determine what email they’ll receive. The email sender benefits if they include those sending preferences at the beginning of their relationship with the recipient.

When we interviewed participants for qualitative insights around this, we gained even more insights:

  • Recipients wish there were more ways to control the frequency and types of emails they receive. 
  • Some recipients would like companies to contact them shortly after they have subscribed to gauge their interest in current email offerings, learn how these can be improved, or help them adjust the frequency of what they receive.
  • Relevant emails are interesting emails, and recipients engage. As a result, recipients would even be interested in providing more than just email preferences, indicating they’d be happy to provide likes and dislikes, sizes of clothing they wear, hobbies/interests, and other details to ensure the emails they receive feel more personal.
  • A few participants felt such a move would convey a company really cares about their business relationship and the dialogue they have with them as a trusted sender.

“It just shows consideration versus shoving stuff down your throat. They care about the customer more than pushing sales.”

U.K. Gen Z

Collect Email Preferences at Sign Up

When you don't collect email preferences at signup, you create more work for yourself by trying to figure out how much email is right for your recipients. In general, once a recipient has made the decision to unsubscribe, they're not interested in updating their preferences at that time.

Chapter 12: Key Differences Between Age Groups

You might think that older email recipients would have stronger, or different opinions than younger email recipients, but in general, that’s not what our research showed. The differences that stood out include:

  • 44% of Millennials want daily emails about products they’re interested in, but only 31% of Baby Boomers want daily emails. 25% of Baby Boomers would prefer getting emails just once every two weeks. 
  • 61% of Baby Boomers said that the sender of an email would strongly influence their decision to open the email as opposed to only 45% of Gen X participants. 
  • 27% of Gen Z and Millennial participants said that the Brand of the email would make it very memorable while only 15% of Baby Boomers said Brand would make an email memorable. 
  • The top-ranked frustration about the inbox for Baby Boomers was Unknown Senders, at 65%. The top-ranked frustration for Millenials was Spam Filters Not Accurate. 
  • Younger age groups indicated they would switch between devices more often than older age groups. 38% of Millennials said they sometimes switch back and forth, but only 27% of Baby Boomers sometimes switch. 
  • The biggest difference between age groups comes in their opinions of GIFs and videos. 76% of Baby Boomers do not want GIFs or videos in their emails. 52% of Millennials don’t want GIFs or videos.

Chapter 13: Key Differences Between the U.S. and the U.K.

Like the different age groups, there weren’t many differences between email recipients in the U.S. and those in the U.K. The areas we did see the largest differences include:

  • 43% of U.S. recipients would actually like daily emails about the products they’re interested in, as opposed to just 31% of U.K. recipients. 
    • Highest Interest – 49% of Millennials in the U.S. would be interested in daily emails.
    • Lowest Interest – Only 24% of Baby Boomers in the U.K. wants daily emails. 
  • The U.K. has a clear hierarchy when it comes to email factors that influence their decision to open an email: Sender, Content, Subject Line, Offer/Promotion, Time of Day
  • Email factors that influence the decision to open an email in the U.S. are more closely ranked: Sender is the most important followed by Content, Subject Line, and Offer/Promotion, which are all very close, and then Time of Day. 
  • 30% of U.S. participants said that Images/Video would make an email very memorable, compared to just 17% of participants in the U.K. 
  • In the U.S., 43% of participants said Critical Information in and email would strongly influence their decision to click on a link within, while only 29% of those in the U.K. said that would be a strong influence. 
  • 53% of participants said that the number of messages in their inbox was something they found frustrating, but only 40% of U.K. participants were frustrated by the number of messages.
  • 37% of U.K. participants said they Sometimes switch from opening messages on their phone to opening messages on their computer compared to just 28% of U.S. participants. 
  • In the U.S., 62% of participants want just a few sentences in their emails, and 33% want 1-3 paragraphs. In the U.K., participants appear to want more content, with 56% wanting a few sentences, and 41% wanting 1-3 paragraphs.

Chapter 14: Highlights and Takeaways for Email Senders

Ensure Correct Email Delivery and Placement – Incorrectly placed email, like when an expected email ends up in the spam folder, frustrates recipients. Learn more about improving your email deliverability in our Email Deliverability Guide

Know Your Customers – Depending on the demographics of your customers they’re going to be more or less willing to engage with emails that have multiple images, videos, or GIFs. If your customer or user base is made up of mostly Baby Boomers, consider leaving those things out of your next campaign. Or better yet, segment your recipients and create emails that they’re more likely to appreciate upon opening. 

Be More Selective – Senders should be more selective with the messages they choose to send recipients. In 2019, recipients are receiving more email than ever before, and companies are sending 8.3 messages per month. In order to stand out to recipients, senders should make sure they’re sending messages recipients are interested in and will value. 

Make Sure Your Messages are Valuable – Recipients are more selective on what they will click than ever before. Even though the open rate dropped to 14.5%, the click to open rate also continued its drop. This means recipients are likely to open an email, but less likely to click on anything. Try to provide recipients with valuable messages that they want to receive. 

Experiment With Frequency – Senders should continue to experiment with their sending frequency. Rather than sending many emails to all of their recipients, try sending fewer messages to more targeted groups to see if your engagement improves. 

Optimize for All Countries – Make sure your email is optimized for inbox providers across the world. Email is one of the most commonly used communication channels in the world. Make sure your messages are getting delivered correctly by properly authenticating your messages.  

Don’t Worry About When to Send – Email is a part of life for nearly everyone, and people with email addresses are typically checking their inboxes multiple times a day. This means that things like the time of day they received their messages are less important than ensuring the content of the message is valuable to each recipient you’re sending to. 

Including Emojis – While it may spice things up a bit, including an emoji isn’t always worth it. Depending on the age of your customers, emojis may come across as unprofessional or spammy, and not as playful and interesting as you may think. 

Content is Important – Many email senders think that there’s going to be some silver bullet they can add to their program, or use in a subject line that will unlock a lot of clicks. This isn’t the case. The one thing senders should think about is providing their recipients with messages they want. Think about segmenting your list and sending more targeted messages to groups of people with specific products or offers that they’ll want to receive. 

Keep it Simple – Email recipients have been using email every day for a long time now, so they’re very aware of what an email should and should not look like. Rather than trying gimmicky things like flashy GIFs and videos, multiple images, or super long newsletters, you’re better off providing a well-designed email with a few sentences of content and a couple of images that illustrate your offer. 

Double-Check Your Work – Grammar and spelling mistakes were some of the biggest turn-offs when it comes to email. Make sure your emails are error-free before hitting the send button.

Chapter 15: Send This, Not That!

Now that you have the data and findings from our research, what should you do next? Below are some tips that we’ve compiled on what you should and should not send to your recipients. Scroll through for a thorough list of things to send (and what to avoid).

Tips that we’ve compiled on what you should and should not send to your recipients
Tips that we’ve compiled on what you should and should not send to your recipients

Chapter 16: Appendix

Metrics Definitions

Aggregate Open and Click Rate: These are percentages of all unique messages sent by a segment that were opened or clicked. Messages that are clicked or opened more than once are not double counted.

Aggregate Delivery Rate: Percentage of all messages sent to valid addresses that were not rejected by the inbox provider.

Aggregate Spam Rate: The percentage of all unique messages that were marked as spam. 

Mobile Ratios: Using the recipient device information inferred using the method described above, devices were categorized as mobile or not mobile. These ratios are the distinct count of mobile/non-mobile devices seen divided by the total distinct count of devices seen. Each device is counted only once per recipient.

Aggregate Monthly Send Rate (Send Frequency): This is the number of unique messages on a per sender per recipient basis. It tells you how many messages an average recipient might see from an average sender in a particular segment.

Aggregate Click-to-Open Rate: This is the ratio of unique clicks to unique opens; duplicates are not counted. This answers the question: “Of the emails that were opened, what percentage were clicked?” It can be thought of as a proxy for content quality.

Recipient Engagement Study Coordination

The recipient engagement study was performed by InterQ Research.

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