3-Step Guide to Crafting Subject Lines

3 min read
August 10, 2022

Subject lines are possibly the most important part of an email. It is the first, or one of the first, things that a recipient will read before deciding to open an email. Even if the rest of your email is well crafted, suited to a specific persona, that hard work will not matter if you use a generic, basic subject line. Most email marketers will feel the need to replicate what they see from other email marketing campaigns, but this may get you stuck in the promotions inbox, otherwise known as gray mail. Subject lines should not only be well thought out, they should be tested. As a start, using subjectline.com can help you to craft an acceptable subject line, and see what makes your subject lines great and what they can improve on. Subejctline.com is free to use, so it is a great start for anyone who is looking to level up their subject line game.  

Basic Do’s and Don’ts of Subject Lines.  


  • Do: cut it down. Long subject lines will not be read beyond the first few words, so make sure you are creating subject lines that are within the character limit of 60 characters. After 60 characters the subject line gets cut off on most email platforms. Making your subject lines even shorter makes it more likely for the entire subject line to be read. 
  • Do: Share some news. Making an announcement with your subject lines engages leads, thinking “some big changes are coming.”   
  • Do:Tell leads to act. While it may seem demanding or off putting. Telling leads to act, and with urgency can help you to get actions based on emails. The trick is doing this in a way that does not come off as spam.   
  • Do: Use your leads location as a reference in your subject line.  
  • Do: Be consistent. If you are offering certain content or a deal in your subject line, then make sure to follow through.  



  • Don’t: Blend into the crowd. If your subject lines similar to other subject lines, your emails will unfortunately fall into the blur of other marketing emails that your   
  • Don’t: Imply that the email is coming from someplace else besides your business. While some companies do this in the hope of raising open rates, this is a good way to permanently end up in the spam folder.  
  • Don’t: Use too many numbers in your subject line.  Too many numbers makes it sound like your are just giving leads the hard-sell…before they even open your email. 
  • Don’t: Use Spammy words. Using words that email platforms could potentially mark as spam could potentially put your emails into a spam mailbox.  

While subject lines don’t necessarily have to follow these rules strictly, use them as a guide. There are some gray areas that experts do not agree on. One being, using first names in subject lines. Using HubSpot’s “personalization tokens,” you can include a leads name in your subject line. But while some swear it improves their open rates, some experts say that using the first name in a subject line can actually reduce open rates. 

How to conduct A/B testing for subject lines. 

A/B testing is when you set up two different variations of a marketing email and send the email out to a small percentage of  marketing contacts to see which one generates more clicks. This can be done for a lot of different parts of an email, not just the subject line. Marketers use A/B testing for  preview text, A/B testing can be done if you want to change your approach to subject lines, but are not totally sure how a group of contacts will receive that change.  Subject lines are the perfect thing to test. A/B testing only works if you test one thing at a time, because when compared to a control, you can know that the variable is what most likely altered the results.   


So how do you conduct an A/B test? Well, since this is a blog on email subject lines, I won’t go too far in depth, but you can run an A/B test on most email marketing software. Choose a small percentage of marketing contacts to test your email with, and split that group into two. With one group, be experimental, and with the other stick to your usual technique. Then, your email marketing platform should generate the results for you. 


Create different subject lines for different buyer personas. 


This goes hand in hand with part 2, A/B testing can help you cultivate better ideas for buyer personas. Buyer personas, depending on how they differ from other personas, will open emails at different rates depending on your subject line, even if the rest of the email is exactly the same. Buyer personas are motivated by different things, so naturally, different subject lines will motivate them to open emails. Play into that motivation, because if you are able to tap into that, then you can motivate them to be engaged


As best practice, first test your buyer personas with A/B testing, and then gather data (through HubSpot or other email marketing software) to guide your email strategy. Some leads may respond better to more urgent subject lines, while others will respond better to more humorous subject lines. Or perhaps you want to specify subject lines by the field of work that the buyer personas are in. The possibilities are endless.  


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