How to Create Irresistible Emails

I spent a few of days in July 2018 at the Denver Digital Summit. This and other blog posts (like this one) are a debrief of some of the sessions I attended during the conference.

Jillian Wohlfarth is SendGrid’s Director of Content. Now, at Growth Guild we do have our preferences for email marketing (a certain ape we won’t mention by name), but Jillian’s session was one of my absolute favorites at this event.

In the last couple of years, companies have gone down from sending 10 emails a month to sending 7 emails a month to their database of users. This downward trend means that click rate and engagement has gone up, because there is less email fatigue in the audience. Marketing departments are making a concerted effort to be more respectful of their audience’s time, which is awesome because the audiences are clearly responding positively to the change.

Still though, there is a lot of competition for that precious inbox time and in order to win, your email needs to prove … well, irresistible.

When it comes to email elements: subject lines, copy, images, these are the best performing trends: 

Subject lines

The most popular subject line length is 7 words. However, the subject lines that receive the most engagement are, on average, 4 words in length. There is an important reason to keep subject lines short: mobile screen sizes. As you can see in the image below, some of the longer subject lines in these promotional marketing messages are getting truncated. And with 55.6% of all emails being opened in mobile exclusively, how can you expect someone to find your email irresistible if they can’t even read the full subject line at a glance?

Subject line email growth trends 2.jpeg

Some other subject line tips:

  • You should be writing your subject line last, after you’ve decided on headlines, body copy and call to actions. Of course, there will be exceptions to this rule, but in general you want to have a really good idea of what your content is before you can decide on how to best distill it into 4 (or 7) words.

  • Don’t be vague. Try to use verbs that resonate with your audience. And, while going for the pun or comedy can get you good results, try to at least provide with an idea of what’s inside.

  • Emojis? Everyone is doing it. None of our data points to them providing noticeable statistical differences in open rates, but it does mean you’re adding an additional word at least to your subject line. Jillian prefers to go without.

  • Personalization (first name tags) won’t influence engagement. People expect you will know their name and address them as such. SendGrid has found more success with emails that instead request subscribers on the first touch to set their personal preferences within the system to tailor their customer experience. 


As far as copy, it becomes more of a branding conversation. You can go back and read our blog post about omnichannel strategy (add a link here) to see how important it is for the tone and voice of your brand to be consistent across all channels of communication. Whether your tone is playful, snarky, academic, etc. your emails should sound like they were written by the same person who wrote your advertising, your blog posts, etc. You can read more about developing a brand voice here.


With a majority of email viewing traffic coming from mobile, it is more important than ever to be mindful of your scrolling. The rule of thumb is 2 lines of contextual copy per image to allow for a good balance of image/copy. Of course, adding alt tags and as much live copy as possible remains important to ensure deliverability.

As far as strategic steps to keep your emails irresistible, Jillian recommends keeping CTAs up in the top third of the email, since certain email clients will truncate emails that are over a certain size. Also, using the data you collect about what your clients are doing and how they are interacting with your products can provide opportunities for personalization. For example, if you have a client that normally purchases ladies’ clothes and suddenly starts purchasing children’s clothes, it is safe to dedicate part of your content to promote children’s clothes in the emails they will be receiving in the near future.


We tell all our clients this, but Jillian confirmed it: testing is one of the most important areas to find quick wins. By A/B testing different features, subject lines, copy, images, call to action, you should be able to identify and implement wins that will serve you well. And once you find something that works, you should continue to test for new improvements over time.

Last but not least, Jillian discussed audience expectations. Once again, we heard confirmation of the importance of creating expectations in the audience and asking for permission before you invade the sacred inbox of an unsuspecting bystander. By providing ample notification of your intention to send emails, as well as an introductory email that allows the user to set their email preferences, you can start your email program on the right foot and create the trust and transparency that will permeate the rest of your brand transactions.

Read more tips about how to collect email addresses for your business.


Astrid Storey