Black Friday & Cyber Monday 2021 by the Numbers

Black Friday & Cyber Monday 2021 by the Numbers

With November behind us, it’s time to look back at the recent holiday weekend. We in the email world consider this the World Cup, Super Bowl, Stanley Cup, World Series, and Olympics of email all rolled into one epic mail sending weekend: Black Friday and Cyber Monday. While 2021 is certainly not 2020, it’s a far cry from our last pre-pandemic holiday of 2019. That said, the one thing that has held true since 2019 through this holiday season is the incredible reliance on email as a means of engaging customers and ramping up the holiday shopping season. 

The big picture

Twilio SendGrid processed almost 6.8 billion emails on Black Friday and just north of 7 billion emails on Cyber Monday.
As in previous years, Twilio SendGrid eclipsed the volume of email traffic processed by a significant amount. In 2021, the Twilio SendGrid platform processed almost 6.8 billion emails on Black Friday and just north of 7 billion emails on Cyber Monday, which represent 16.9% and 22.2% year-over-year (YoY) growth from 2020. The Twilio SendGrid platform performed brilliantly while maintaining a peak burst rate of 530 million requests per hour!

On numerous occasions, pundits have predicted the death of email—for example, collaboration tools were supposed to be a nail in email’s coffin. Social media was also sure to bury email given its meteoric rise. However, what email has proven time and again is that the internet’s original communication channel isn’t only alive and well but thriving. What these pundits seem to miss is that every new service, forum, platform, and network leverages email, in addition to other means to create accounts, transact, recover passwords, etc. With email, it’s never “email or [new shiny channel],” it’s always “email and [new shiny channel].” 


If we look back at our sending volume during the month of November from 2009-2021, you can literally see how our mail volume began to reflect more and more commercial email. When SendGrid was founded, it was built as a transactional email platform. However, crafty developers decided that SendGrid’s platform was too powerful to be limited to just transactional email, so they began to tie our APIs to any customer communication need that arose during the customer’s journey. That didn’t totally happen by accident. Today, you can see the peaks and valleys of normal sending during the week, with a fever pitch reached on every Black Friday and Cyber Monday. 


Apple Mail Privacy Protection

Besides Brand Indicators for Message Identification (BIMI), the largest change to the email ecosystem during 2021 was the rollout of Apple’s Mail Privacy Protection (MPP). Since this rollout in the last major iOS update, we’ve been monitoring and measuring the impact of machine opens: The caching systems downloading everything from the splash graphics at the top of an email creative to the tracking pixel nestled at the bottom of the same creative. 

Although the tracking pixel has been a staple of email marketing, it’s quickly becoming obsolete because a good portion of the email sent is being anonymously opened, so it’s impossible to tell if it was opened by a machine or a human. As a signal of intention, it’s hard to justify strategy based on an anonymous interaction with a given email. 

In order to help marketers adapt and make these anonymized opens easier to segment out and disregard, we launched the Apple Machine Open Indicator. Due to the increase in anonymized engagement, marketers are challenged to look elsewhere to determine intention and engagement. Based on our observations, MPP opens on Black Friday were just over 40%, and on Cyber Monday, just shy of 40%. This shows a significant penetration of the feature among recipients reading their emails on Apple mobile devising, iMapping, or popping their Gmail into these devices or on their MacBooks and tablets using native Apple email readers. 



Words matter

Subject lines are like that old Head & Shoulders commercial that aptly said, “You never get a second chance to make a first impression.” This couldn’t be truer than when it comes to subject lines. If you weren’t in a tryptophan haze on Black Friday, you probably saw everything from an abundance of exclamation points in your inbox to emojis that were more hieroglyphics than any decipherable language. 

However, as in previous years, we took a look at how subject line length (word count) affected open rates. The old adage that less is more held true again. Pithy subject lines had the highest opens, with 4 or fewer words clocking in at a unique open rate of just shy of 14%. As the length increased into the double digits, that unique open rate dropped off. The moral of the story here is be concise. Attention spans are short, and there’s a lot of email in everyone’s inbox, so you need to cut to the chase, deliver a meaningful message, and save the epic for the body. The following chart factors out machine open rates to focus on measurable human engagement. 

Black-Friday-Cyber-Monday-Unique-Open-RateTiming is everything

When I first started my career in email, it was an accepted fact that Tuesdays and Thursdays were the “high volume” days for email marketing. Today, it seems like every day is ripe with emails flowing to inboxes. However, we wanted to know how the massive volume of emails we observed on Black Friday and Cyber Monday were sent through the course of the day. Early on, we saw a good spike around midnight—these were no doubt the early birds. However, it meant that their emails were most likely to be lower down in the list view. Keep in mind that volume drops off as the day progresses but picks back up around noon and goes full speed ahead into the evening. 

We saw more or less the same mail distribution on Cyber Monday, with the highest volume of email being sent between 3 p.m. and 9 p.m. PST.

When they open

If you think about email as a series of microdecisions that lead to a conversion, then the next natural action or decision you want a customer to make after receiving an email is to open it. It should come as no surprise that Black Friday and Cyber Monday feature a captive audience that has been trained over the last 10-15 years to expect opportunities and deeply discounted offers in their inbox. We took a look at how long after an email was delivered that we cataloged an open event. Then, we focused specifically on conventional opens rather than anonymized opens.


Not surprisingly, opens happened more or less in line with the delivery window and were proportionate, suggesting that people were not opening wild amounts of email from earlier in the day. The one exception on Black Friday was the 12-3 p.m. hours, where we saw a much larger percentage of opens vs. the volume sent in that same time frame. 

The same exact pattern was repeated on Cyber Monday without too many discrepancies. We saw nearly 50% of all email traffic sent between noon and 9 p.m. 

Clicks should be our North Star

With the advent of Apple’s MPP feature, marketers have been forced to look at other metrics to distill an understanding of how recipients interact with their messages, and how those interactions lead to conversions. Clicks have manifested as paramount to that understanding, in addition to other vectors, such as how frequently someone clicks, if the clicks happen multiple times on a single email, etc. We wanted to understand if the click following an open happened in roughly the same time frame as the open. Not surprisingly, we saw a general theme that most clicks happened around the time of the open, and the pattern we saw with opens seemed to mostly hold true for clicks.

Black-Friday-Cyber-Monday-Percent-of-MessagesThere seems to be a slightly different pattern of clicks on Cyber Monday, but that may just be a factor of people being back at work.


In addition to understanding how long it took for email to be opened after it was sent, we wanted to understand how long it took people to click a call to action or another link within the email. The median open time, based on unique opens of delivered emails, ranged from 45 to 59 minutes, while the median click time after messages were opened was around 12 seconds. For senders, relying on time-sensitive offers considers that, on average, it may be as long as an hour before someone opens their email. However, if your offers are engaging enough, the desired outcome of a click to reach your mobile app or website can come rather quickly.

Generosity surges on GivingTuesday

Retail sales aren’t the only thing skyrocketing at the close of November—so is the incredible generosity of philanthropists. GivingTuesday, which falls on the Tuesday after Thanksgiving each year, is the nonprofit sector’s largest fundraising day for email. 

GlobalGiving, a nonprofit that connects nonprofit partners to donors and companies, relies on Twilio SendGrid’s Email API to power its massive GivingTuesday campaign. The nonprofit sends upward of 1 million emails to draw in donors on this crucial date. Personalized subject lines and A/B testing yields high engagement from donors, who are more likely to engage with content tailored to the causes near and dear to their hearts. The proof is in the data:
  • Unique opens: 185,800
  • Average open rate: 23.64%
  • Average click-through rate (CTR): 1.58%
  • Funds raised: $305,583.16 spread across a total of 10 targeted email sends
  • Unique clicks: 12,526 
  • Average subject line length (# of words): 8 
This year, GlobalGiving’s strategy balanced experimentation with personalization by inspiring donors to give with a specialized subject, preview, and body copy based on their giving history. A series of A/B tests measured the impact of this customized copy on the organization’s most valuable donor segments. This strategy yielded open rates that were 25% higher and CTR rates that were 5% higher than GlobalGiving’s 2021 average. The nonprofit’s highest performing email was its last call for donations, which featured a punchy subject line and an eye-catching countdown timer embedded in the header. This email achieved nearly a 30% open rate and a 2.1% CTR. 

Following the 2020 giving blitz sparked by COVID-19, GlobalGiving saw a slight YoY decrease in 2021 Cyber Weekend results as shown below. However, when compared to more standard fundraising results seen in 2019, 2021 volume marks a 30% increase YoY—indicating that charitable giving is stronger than ever this holiday season. 

That’s a wrap!

The email marketing landscape is changing. Some of the changes are challenging marketers to reexamine established measures and find new ways to gauge engagement. Other changes are evolutionary and signal how the email inbox is evolving and becoming more user-friendly and visually appealing with the general availability of BIMI at Gmail. Email is a dynamic and evolving medium that underpins and powers the many services and platforms that have evolved on the internet since the first email was sent in 1971. And this year, email celebrated its 50th birthday! That’s right, email has reached the half-century mark, and we couldn’t be more excited! 

This year’s Black Friday and Cyber Monday saw the processing of almost 14 billion emails across both days through Twilio SendGrid. If nothing else, this staggering volume shows the investment that businesses around the world place on email as a vibrant and crucial channel to deliver communications that help us all feel a bit more connected in what is the second year of a global pandemic. Contact our experts to ensure your email program is built for growth.

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