BOULDER, Colo. — SendGrid, the leading email delivery platform for email that matters, today revealed the results of a study on global email engagement. In conjunction with the 33rd anniversary of the invention of email, the data was collected over two 10-day periods in 2014 and 2015 respectively, with a data set spanning more than 10 billion emails sent.

The findings include:

  • Apple-manufactured devices retain the crown as the most used platform to access emails. Nearly half of email opens in the US (45%) tracked by SendGrid have been accessed on Mac desktops, Macbooks, iPhones and iPads.
  • Windows-based devices are the second fastest growing segment for email opens globally. On average, emails opened per day on Windows devices in the last year, accounted for a 3.39% increase over the prior year.
  • Android and Linux based devices are the two fastest growing segment for email opens in the US, growing 71.4% in the last year.
  • Canada is the largest region for email readership, representing 7.9% of email opens in the last year. Australia is third in email readership, with 7.0% of email opens in the last year.

According to a report by Vision Mobile, the global app economy is projected to grow to $143 billion by 2016. App developers, CMOs and SMB owners will continue to leverage email as the number one customer engagement tool to drive adoption and retention.

SendGrid continues to see a rapid growth in email usage and is now sending more than 20 billion emails per month for an expanding base of customers which includes CBS Interactive, Taco Bell, Spotify and Airbnb.

“Email remains the standard for online B2B and B2C communication, despite the rise in over-the-top (OTT) messaging and social media platforms,” said Aaron Beach, senior data scientist, SendGrid. “Email is the world’s number one engagement tool and is still the most cost-effective way for companies to interact with their customers.”

Most brands engage customers by sending marketing and transactional emails, which include receipts, password resets, notifications, social alerts and promotions.

SendGrid additionally analyzed 5 million unique subject headers in nearly 18 million emails. The study provides marketers with insights on how to better tailor their campaigns to drive stronger email engagement through opens and clicks.

The key findings revealed:

  1. Shorten Subject Headers: While 7 words is the most common subject line word length (14.0% of subject lines), 3 word subject lines (1.6% of subject lines) have the highest engagement rates (21.2%, compared to 17.2% overall and 15.8% for 7 word subject lines).
    • Measuring engagement rates by number of character lines tells a similar story: longer subject lines have lower engagement rates. Past 15 characters, each extra character is correlated with a 0.03% absolute decrease in engagement rate (or about 1% per 33 characters).
  2. Choose Your Buzzwords Carefully: Recipients prefer certain words over others. Subject lines referring to “yesterday” and “tomorrow” have higher engagement rates (20.5% and 22.3%, respectively) than “today” (11.8%).
    • Subject lines with “soon” have higher engagement rates (21.9%) versus subject lines referring to now “now”
    • Email subject lines that use the word “free” have significantly lower engagement rates (13.1% versus 17.2% for “free”-free subject lines).
  3. Eliminate Links and Hashtags: Subject lines that contain URLs do poorly, with average engagement rates of 9.9% (compared to 17.2% for subject lines that do not contain a URL). Subject lines with URLs in them are rare (fewer than 0.4% of emails).
    • Subject lines that contain #hashtags do poorly, with average engagement rates of 10.5% for subject lines with a single hashtag (compared to 17.2% for subject lines that do not contain a #hashtag). Thankfully, emails with hashtags in them are rare (fewer than 0.2% of emails).

The send volumes displayed represent the average of two samples of opens and clicks from SendGrid's data. ...

The growth of email usage over mobile devices will compel brands to adopt a more sophisticated email marketing strategy in order to spur customer engagement and find innovative ways to improve customer experience as well as drive business success.

There is a growing need for new email marketing platforms to allow for effective use of email optimization to help organizations send mail that is both wanted, appreciated, and even anticipated.

About SendGrid

SendGrid is the leading email delivery platform for email that matters. SendGrid’s proven, cloud-based email platform successfully delivers over 20B customer engagement emails each month for Internet and mobile-based customers like Airbnb, Pandora, Hubspot, Spotify, Uber and FourSquare as well as more traditional enterprises like Walmart, Intuit and Costco. For more information, visit

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