5 Email Subject Line Best Practices

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Mark Kilens
Mark Kilens



Email subject lines are the most important thing to get right when doing email marketing. A poor subject line could cause your email to go unopened, get caught in spam filters or worse, cause people to unsubscribe from your list. 

email subject line best practices

An email subject line should be like a call-to-action. Of course, the action you want someone to take is to not only open the email, but to do something in the email. During the Inbound Learning Broadcasts we explain why every email must have a call to action and a specific goal.


 1.  Action-Oriented

Having an action-oriented subject line makes the email standout from the other emails in their inbox.  Consider starting the subject line with an action verb such as learn, download, register or sign-up.   Subject lines should speak directly to the recipient in an active tone, which will result in getting them to notice the email and open it.

Another tip is to use one keyword in the subject line that people will recognize. The keyword should be a non-branded keyword like “blogging best practices.”  Branded keywords are good to use in the emails “from” name and can be used in the subject line as well.

2.  Compelling

One of the steps in our 8 Step Call-to-Action Guide is to make calls to action compelling and it shouldn't be any different with email subject lines. Afterall, you only have a couple seconds to grab the attention of people skimming through their inbox. Make sure you include the email’s offer in the subject line, so people know the value the email will provide them. Creating a sense of urgency is a good tactic to use in conjunction with the compelling offer.

One way to do this is to use brackets in the subject line. For example, you might be promoting an upcoming webinar and you want to make sure recipients realize this right away. Your subject line could be, “Learn to Become an Efficient Blogger [Webinar in Two Days]

3.  Non-Spammy

You can’t afford to have your subject line get caught in spam or firewall filters. Therefore, you should be very careful when choosing what words you put in the subject line. Excessive punctuation mark  and and words like free, act now, offer, or credit will almost always get flagged by spam filters.

4.  Consistent

The two things people will see before they even open your email is the subject line and the preview text. This is because most people use the preview function in their email client to determine if they want to spend the time reading the email.

You want to keep the first couple sentences very consistent with the email's subject line. They should reinforce and add to the compelling offer and should be action-oriented. I recommend including a link in the first or second sentence that sends them to the page you want them to take action on.

5.  Short

Email subject lines cannot be very long. I recommend you keep them under 45 characters or you run the risk of people not seeing the entire subject line. You also want to put the most important and compelling information in the beginning of every subject line. The best way to determine an effective subject line will be to run A/B tests to see which one has a higher open rate.

To learn more about how to send great emails, register for our free Email Marketing Certification course.

Photo credit: derekfredrickson.com

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