How to Write a Good Email Subject Line

Keep them short and sweet with a reason to open the message

Hands of man writing e-mail
Nico De Pasquale Photography / Getty Images

Given that many people receive around 100 emails a day, it can be hard to get yours noticed. That's why the subject line is critically important. After your name, the subject line is the first thing the recipient sees and, depending on its quality, may make the difference between your message being promptly opened or fading into "slipped through the cracks" territory.

What Makes a Good Email Subject Line?

The most effective subject lines are brief and contain a reason for the user to open the message. Keep the recipient in mind and know what you want from them. If the message requires action, include it in the subject line. For example:

  • Computer support needed
  • RSVP requested for company retreat
  • Please review attached monthly report

If the action associated with your message entails a date or deadline, include it in the email subject as well:

  • Computer support needed ASAP
  • RSVP requested for company retreat - respond by October 15
  • Please review attached monthly report by Friday

Be brief but include enough detail for the recipient to know what the email is about. It's okay to skip unnecessary articles, adjectives, and adverbs to keep the word count down. Studies recommend limiting the total number of characters in a subject line to between 30 and 50. If we apply these rules to our subject lines above, we get very concise phrases:

  • Computer support needed ASAP (30 characters including spaces)
  • RSVP by October 15 for company retreat (40 characters including spaces)
  • Review attached report by Friday (34 characters including spaces)

Using a question as the email subject can draw a reader in:

  • Are you attending the company retreat?

Sometimes a directive works well:

  • Join us at the Miami retreat!

You can imply scarcity to get recipients to act:

  • Only 5 tickets left for Miami retreat

Or try tempting them with a list:

  • The 5 sessions you won't want to miss in Miami

Don't tackle more than one topic in a subject line. If your email includes multiple subjects, send multiple messages. That way, one topic won't get lost in a thread about a different one.

Whichever approach you take, keep subject lines short and to the point to get the best recipient response.