January 6, 2022
Keep it short. Shorter headlines tend to work better. Plus, they adapt to the space allotted for subject lines on mobile, about 40 characters. Headlines for desktop email span 50 to 65 characters. As you'll see, a well-crafted subject line can do yeoman's work for both devices.
Put the juicy words first. Our email audience is short on time as they check through their email. They have no interest in stopping to figure out what your subject line is about. That's why we use juicy words as close to the beginning of the subject line as possible.
A juicy word might convey the news in the email. For example, T25 "Ultrasound Unit Helps find Shipwreck" rewrites to "Shipwreck found with T25 Ultrasound Unit," which is far more tantalizing. So, check your word order and make sure the juiciest tidbit is upfront.
Avoid words that trigger spam blocks. You want your email to make it to the inbox, right? Then don't use words that alert SPAM filters on servers. There's a gaggle of these. But, in general, they ooze hype, like "The world's best nutraceutical," "new and improved," "50% Off", and money and dollar signs. For more, read our post on "Words that make Spam Filters Grouchy."
Don't be too clever by half. When in doubt, be concise and direct about the content of your email, for example, "Board of director's reception, 7:30 pm, Mon," as opposed to "Be Board on Monday night." Unless you're performing an A/B test with two subject lines competing against each other, you may want to drift toward the straight version.
Mate the subject line to the interior copy. Think about your subject line and the first heading as a two-part headline, like this subject line: Cancer Expert Speaks at AAO Booth, and inside subhead: Dr. Martin discusses AI in cancer diagnosis. Otherwise, your user may be as confused as heck and move to the following email in their queue.
Considering all the work you've invested in copy, design, and programming, it's well worth your time to take a few extra minutes with your subject line(s) to increase the chances that your email gets opened.