When it comes to copy, the subject line is one of the most valuable pieces of real estate in your email. The subject line helps determine what action a subscriber will take (or not).

A great email subject line prompts subscribers to open your message and continue reading. They might also motivate subscribers to go directly to your website without reading the email. Effective subject lines build credibility and trust with your subscribers while poor subject lines can result in subscribers deleting your email without taking any action. Even worse, bad or downright misleading subject lines can also cause subscribers to mark your email as spam or junk, which in turn can impact future email delivery rates.

So how do you write a great subject line? And how can you avoid terrible subject lines? Here are some tips for subject lines that spark opens and subscriber action.

Keep subject lines to 50 characters or fewer. Research continues to show that shorter subject lines are better. Fifty characters amounts to about 6-8 words, including spaces.

Know your brand, and write your subject line accordingly. If your brand is fun and quirky, then you’ll want to consider a cheeky subject line. If your brand is serious, then your subject lines should take a more formal tone.

Answer what’s in it for me. To open an email, subscribers want to know that doing so will benefit them. In other words, your subject line should be relevant to subscribers. Consider the value your email provides, and write your subject line accordingly.

Be clear. Tell subscribers what they can expect when they open your message. No one likes to be duped, so avoid misleading subject lines. Plus, misleading subject lines are a violation of U.S. CAN-SPAM legislation.

Use calls to action, but don’t come on too strong. Using a call to action in a subject line is a great strategy, but stick with a low-commitment request. High-commitment calls to action can be off-putting for subscribers. Consider the following two subject lines. Which one are you more likely to click?

• A: Purchase 10 new looks we’ve prepared for you!
• B: See 10 new looks we’ve prepared for you!

I can think of a few reasons to not open subject line A: I don’t want to spend the money, I don’t have the time to shop. Delete. Subject line B, however, is much easier to open. Sure, I can take a quick look. Oh, man, there are those pants I’ve been browsing matched with an adorable sweater. Where’s my credit card?

Don’t sweat the “spammy” words. A quick Google search will yield numerous lists of words to avoid in email subject lines. Many fear that using a word like free, win, new, clearance, sale, mortgage rates or never will trip spam filters. So what should you say if you are giving away an item to a lucky winner, or you’ve just put new items on sale? Or, you are a lender and you’d actually like to tell your customers that mortgage rates have decreased? Say what you mean. If any of these “taboo” words are relevant to your message and audience, use them. If you’re concerned about inbox deliverability, please see the recent blog post we wrote on this subject, or contact your account manager or .

Break the rules on occasion. What fun are rules if you don’t break them sometimes? If you have a compelling reason to break any of these guidelines, do it. Sometimes writing the same style of subject lines over and over causes monotony. Breaking the rules — even if it’s writing shorter or longer subject lines or a very direct call to action — can grab the attention of previously disengaged subscribers.

Test, test, test. We just can’t say it enough. It’s the beauty of email marketing. You can test your theories! Use A|B split testing to gather audience-specific insights. Test high- vs. low-commitment subject lines or the length of a subject line. You could test different key words or whether using an emoji boosts open rates. Remember to test just one variable at a time.

Can we help you write subject lines that drive higher open rates? We’d be happy to provide feedback on one of your future subject lines. Contact us at (314) 918-8088 or .