Lyris HQ has a great a white paper "Email Subject Lines: 15 Rules to Write Them Right," which highlights the make-or-break importance of subject lines. It's well worth taking a few moments to go through their registration and obtain your own copy, but here are my favorite highlights:
- Test! Test subject lines. Write them early (not at the last minute). Test again, measure results, and use those analytics to drive future content.
- Structure and content are both important. You need to be cognizant of where the key info goes, as well as how strong your call-to-action is.
- Subject lines play into trust-building. The subject line can include a branding element or another device to tie to the "from" address. A quick way to kill that positive messaging? Stretching the truth about what's inside the message.
Here's a breakdown of their entire list:
- Read the newspaper. Newspaper headlines highlight a story's most important fact in a limited space-which is coincidentally exactly what marketing email subject lines should do.
- There is no sure-fire formula. Subject lines are non-recyclable and not necessarily the same when sending different types of campaigns.
- Test, test, test. According to rule 2, there's not a surefire winner, so be sure to allow time for testing.
- Support the "from" line. The "from" tells recipients who sent the message, and the subject line sells that recipient on whether to open it. You don't need to repeat your company name in the subject, but do consider some subject-line branding (ex: the name of the newsletter).
- List key info first. Put the key information in the first 50 characters. Not sure where the subject line will be cut off? Send it to yourself to test and check!
- Open rates don't always measure subject-line success. Your end goal is not necessarily high open rate, but to have subscribers take a specific action. Focus on those results instead of open-rate numbers.
- Personalize. Personalize subject lines based on your recipients' content preferences and/or interests, and then be sure to make it easy for readers to find and update this information upon receiving your message.
- Urgency drives action. Set deadlines for action, and consider using a series: "Only five days left until...!" followed up later in the week with, "Just 24 hours left until..."
- Watch those spam filters. Run your copy through a content checker to identify spam-like words, phrases and construction. A couple of big no-no's: all capital letters and excessive use of exclamation points.
- "Free" is not evil. As a follow-up to number 9, avoid putting the word "free" first, but you needn't leave it out entirely.
- Lead, but don't mislead. Subject lines are not the place to overpromise. Be truthful about whatever the text claims to avoid distrust.
- Write and test early and often. Flip your thinking: Craft and test your subject line prior to composing the rest of your message. (Remember rule 3?)
- Review subject-line performance over your last several campaigns or newsletters. Not only will this type of data-mining shed light on your subject-line successes (highest conversation rates, click-through rate, etc.), it will drive future content strategies.
- Continue the conversation. Sending campaigns more frequently than once per month or quarter helps create a back-and-forth with readers, and also allows for content follow-up if something from a previous campaign has news.
- Can you pass the must-open/must-read test? Must-read means this: If a subscriber doesn't open the email, they will feel like they are out of the loop and may have missed an offer they will regret not taking advantage of. Also, be sure to check out whether your message is going to the bulk-folder (see rule 9).