What Makes a Good Subject Line?

And you thought writing a 140 character tweet was difficult…

There is an art to writing a killer subject line. The most important tip is to do your own testing with your audience to see what works.

Here are a few things to take into consideration…

The Shorter The Better

Subject lines should be under 50 characters. People don’t have all day to read your content. There is only so much time for content consumption.

Not all inboxes show subject lines longer than 50 characters. It also varies based on the device you’re using. You’d hate for your subject line to get cut off in an awkward spot that would change the meaning of what you intended.

Keep your subject lines short and sweet.

Avoid Danger Words

Avoid spam filters by following these tips:


Bait and switch tactics might get you a few more opens, but will get you nowhere if you’re trying to make a sale or if you’re thinking long-term (which you should be). Your subject line should clearly communicate what is in your email.

Curiosity Did Kill The Cat

Appeal to your audience’s sense of curiosity by giving your reader just enough to want to find out more.

Examples of Subject Lines Appealing to Curiosity

  • What’s yellow, leather and on sale?
  • See what awaits you at bacon fest…
  • Check out fashion star [name here]’s, fashion fail

Don’t Read This

Of course I’m going to read further if you tell me not to. Try a little reverse psychology with your subject lines.

People love doing the opposite of what you tell them. It appeals to their rebel side.

Personalized Subject Lines

Personalization, when used in the right context, has been proven to be a good strategy to boost email engagement. Tread carefully when including a first name in your subject line. Sometimes doing this can hurt your open rates but like everything in marketing, your audience may respond better or worse than some of the studies that have been performed.

Use Localization

Using localization is a great way to personalize your subject lines. Do you have multiple locations? Your customers probably don’t want to receive an email pertaining to a location they will never visit. Sending an email that is useless to your subscribers can lose their interest in a quick hurry.

When signing up a new subscriber, consider asking for their preferred location or their zip code. The more information you require when asking for email sign-ups the lower your conversions will be.

Consider Your Audience

While there are many different ways to write a great subject line you can’t forget your audience. What might work for some industries may fail for another.

Test various subject lines to see what works and what to avoid with your audience. There isn’t a one-size-fits-all for subject lines.

Happy emailing!

Sarah Shuda
Sarah Shuda
Designer. Mom. Wife. Loves Gilmore Girls, healthy living, and long walks in the country.