The 11 Dos and Don’ts of Email Subject Lines

Spoiler alert: there’s no silver bullet for subject lines.

Let’s go through a few of these dos and don’ts to get an idea of current email subject line best practices.


1. Use questions. A recent study by Mailchimp found that subject lines phrased as questions performed better than similar subject lines that were phrased as statements.

2. Keep it short. The same study by Mailchimp found that longer subject lines performed worse than shorter ones. If possible, they suggest keeping your subject line under 50 characters (In a 2012 study, MailerMailer found that short subject lines, specifically with fifteen characters or fewer, had the highest open rates).

3. Make sure it’s clear who your email is from. You don’t want your email recipients to be confused when your email shows up in their inbox. If necessary, use a consistent identifier (for example, including your company or product name in brackets at the beginning of a subject line, like [New Pardot Features] for a new feature email).

4. Include a call to action. Sometimes, it’s helpful to clearly inform readers what their next step should be. Otherwise, their eyes will just skim right over your subject line without understanding that an action is required on their part.

5. Convey a sense of urgency and timeliness. The shorter the amount of time that recipients have to act, the more compelled they will feel to do so.

6. Be specific. When people read your subject lines, it should be obvious what your message is and why it’s relevant to them. Leaving your recipients guessing can cause frustration and lead them to ignore or delete your email.

“When it comes to email marketing, the best subject lines tell what’s inside, and the worst subject lines sell what’s inside.” – Mailchimp

Do Not:

1. Use special characters in your subject lines. These have not been known to increase clicks, but have been known to occasionally trigger SPAM filters. Another recent trend is including symbols in subject lines, and while this may increase open rates, the jury is out on whether or not it affects clicks.

2. Send out emails asking for help. Litmus indicates in their infographic that the fear of being scammed has made many consumers wary of emails that always ask for help or assistance.

3. Include first names or personalization in subject lines. In a study conducted by MailerMailer last year, click-through rates and open rates were both negatively impacted by personalized subject lines.

4. Include numbers. While numbers can often increase engagement levels and pique interest, they also put your email in danger of getting lost in the abundance of “special offers” floating around in cyberspace.

5. Use all capital letters. There’s really no need to shout your message at your email recipients. Trust us, they get it.

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