In e-mail, the subject line bears 90 percent of the responsibility of motivating the recipient to open the message. Just like pick-up lines at the local bar, there are original ideas that will get you past "hello," and then there are those stale, corny approaches that cause the other person to move on with eyes rolled back.
E-mail messages face some unique hurdles in grabbing attention amid the in-box clutter. Most marketers would agree that you have to build value with your messaging, but if you don't exercise a good process for selecting and testing subject lines, your value may be lost before you can even say "hello." Assuming you are testing, your timing is right, and you are in "pole position" (not buried 50 e-mails down or filtered to the SPAM folder), your approach can win fans and entice consumers to respond and convert. The biggest challenge then is how to draw the eye, when every other e-mail in the in-box shouts "$$" or "ACT NOW," distracting the consumer's attention.
Too many e-marketers, caught in the day-to-day grind, keep repeating the same marketing techniques; or else they just don't know how to implement what they have learned. So, taking into account you may be doing good segmentation, managing deliverability well, and being upfront and honest with your customers, the next step up on the marketing sophistication scale is to move new customers through a progressive relationship building program, using subject lines that go from sheer attention grabbing to contextual.
I take the white-coat approach to subject lines. I observe, hypothesize, predict, test, and test again. There are three primary types of subject lines in my view and within those types, a few key variables, all of which should be tested against each other. You should continue testing combinations until you find out what works for each type of communication and kind of customer. Some respond to direct approaches and others, like those in a bar who can't stand those cheesy pick-up lines, don't. The three principal types of subject lines are:
1) Brand-centric subject lines. Readers open these because they recognize and trust your brand. Examples: "The gift of Starbucks coffee" or "Walt Disney on the Pirates of the Caribbean."
2) Value-based subject lines. These lead with the benefit statement, encapsulated in 50 characters or less. Example: "david33167, save with this eBay coupon."
3) Action-oriented subject lines. These vary from the blatant "Act now" messages to subtler combinations of incentives tied to an action or deadline. Example: "Claim Your Complimentary Subscription -- Act Fast!"
Within these categories, some variables that are important to test include personalization, word order, combination phrases, case usage, numbers, and symbols.
Michelle Eichner, founder of Pivotal Veracity says, "Marketers sometimes have to sacrifice great copy to improve delivery rates, so be certain to run your subject lines through SPAM checking software first."
In addition, an emerging e-mail culture requires us to adopt e-mail etiquette in subject lines. For instance, all upper case indicates you are YELLING, so lines like "ACT NOW" may seem unreasonably aggressive to many of the more savvy Internet users.
My methodology is to test each category against the others and reserve the more aggressive testing tactics for non-responders, while being more gentle or "formal" with new customers and existing customers.
The biggest mistake I see in subject line testing today is testing solely on the offer itself (does $50 off pull better than $25 off? Does offering free shipping make a difference? -- and so on). Remember the top hierarchy of an e-mail:
1. The subject line conveys the relevance of the communication
2. The opening statement in the e-mail supports the subject line and provides the main call to action/promotion/key message.