What is a subject line in an email?

The subject line of an email is a short piece of text that gives a summary of what the email will be about. When writing an email, you have the option of writing a subject line and this subject line is what will appear in the inbox of your recipient as the title of your email. On clicking on that subject line, the recipient will be able to read your email.

So what’s the ideal length of an email subject line?

For many experts, 41 characters is the best length for an email subject line - though generally, it’s best to keep the lines as short as possible where you can. Research shows that shorter subject lines have better open rates - an important metric for marketers.

👉 Pro Tip: Test your email subject line with our free tool.