Below you’ll find our collection of subject line writing wisdom, based on helping clients transition to effective mobile-first email marketing.

Be forewarned, however, that these are best practices based on our overall experiences and your results may differ. When it comes to mobile email marketing, that testing is even more important given the small screens and short attention spans of your subscribers.

Keep your subject lines short and sweet

• In our experience, we have found that 28 to 36 characters deliver the best click rates.
• And we have found that 6 to 10 words deliver the best open rates.
• Medium length does not perform well, as far as we can tell.
• Long subject lines sometimes work, but this can only be determined by testing.
• In addition to keeping your subject lines short and sweet, you need to frontload your subject line since there’s a chance your subscriber will only see a couple of words at first. Put words with the most impact at the beginning, like verbs.
• And always be running A/B split tests on your subject lines. It’s such an easy thing to test, and your subject line is such a critical step in getting an email opened and acted upon…if you have enough data…why wouldn’t you test every time?

Be visually different to stand out in the inbox

Have you noticed an increase in special characters in your inbox? From smiley faces to arrows to hearts. However, you don’t have to get that fancy to stand out. Even traditional characters such as pipes and parentheses and em dashes can work to catch someone’s eye as they’re doing a quick scan of their smartphone.

But do look into the special characters too. There is increasing support for emojis in subject lines, and quite frankly, we’re surprised we don’t see more of them. Granted, the use of such gimmicks needs to be brand appropriate, and of course you need to test everything, but if this is some uncharted territory that might work for you, try it!

Speaking of testing…

If you’re not sure what to test in your mobile subject lines, here are some ideas to get you started:

• Try being ultra-specific, stating your exact offer: “Save 30% on Your Annual Subscription”
• Numbers almost always work, so definitely try those: “Master meetings in 3 steps”
• Put your call to action in your subject line, like: “Upgrade Today”
• Use a fear factor: “Claim your URL before…”
• Use scarcity: “First 100 trial users get this..”
• Ask a question “Prepared for your Trial Expiration?”
• Awaken their curiosity: “Why selling $10,000 is easier than $250”
• Be timely: “[Upcoming Calendar of Event]”
• Create a sense of urgency: “24 Hours Left”, “Last Chance”

Proceed with caution!

Some habits die hard, even in email marketing. Below are some things marketers used to do that simply don’t work any more (if they ever really did), especially in mobile email marketing:

• First Name personalization: This is just seen as gimmicky and spammy now. Subscribers would much rather get content that’s targeted to them in a very specific way than be addressed by name and served up generic content.
• Adding FW: and RE: These might be the epitome of spam. Seriously. Check your spam folder and count how many times you see these.
• Too many of the same type of special offers: Don’t keep touting the same deal in every subject line of every email you send.
• Reliance on open rates: This is not how you measure the effectiveness of your subject lines, because a high open-rate does not always equal a high click-through rate or conversion.

The best and worst words to use in subject lines

We can’t give you the Holy Grail of subject lines, but we can tell you what we’ve learned works (and doesn’t work) in email marketing when it comes to mobile. As always, test and test and test again to be sure, but in general, we’ve seen good results from these words…

• Upgrade
• Just
• Go
• Better
• Deserve
• Your

…and poor results from these:

• Miss
• Deals
• Out
• Year
• Learn
• Register

Finally, how to do a subject line review

Once you’ve followed the best practices outlined above, take a good hard look at the subject lines you’re using and see if you can’t improve them even more based on the answers you give to these questions:

• Is it useful or valuable?
• Does it promise a reward?
• Is it front loaded with the best words?
• Can you make it more specific?
• Does it trigger a strong emotion?
• Does it contain something very familiar to the reader so that he immediately nods upon reading it?
• Would the subject line be stronger if you add an action to it?
• Could you can add an element of intrigue without misleading?

Mobile email marketing ain’t going away and the subject line will only continue to increase in importance when it comes to garnering the attention of busy people looking at tiny screens. Sure, it’s only a few words, but don’t ever downplay the importance of those few words in getting your email noticed and opened.

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Art by Justin M. Buoni // Just Justin Art

Words by Gerald Marshall // Email Industries

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