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Email Subject Line Tester

Check a subject line before you send it. See its length, spam-trigger words and emoji, and how it will look in the inbox.

Runs in your browser · nothing uploaded

Runs in your browser. Nothing is uploaded.
The short line inboxes show next to the subject.
Score 0 out of 100
0
Characters
0
Words
0
Emoji

What the analysis found

    Type a subject line to see the analysis.

    Inbox preview

    How the subject and preheader get cut off at each width.

    Gmail, desktop
    Your Company
    Outlook, desktop
    Your Company
    Mobile
    Your Company

    A subject line has one job, getting the email opened, and it fails in small ways you cannot see while typing. It gets cut off on a phone, trips a spam filter with the wrong word, or reads as shouting in all caps. You only find out after you have sent it.

    This tester shows those problems first. Type the subject and the preview text, and it scores the line, flags what is working against you, and renders how the line appears in Gmail, Outlook and on a phone. Everything runs in your browser, so nothing you are drafting leaves the page.

    How it works

    1. 1

      Type your subject line

      Add the subject and, if you use one, the preview or preheader text.

    2. 2

      Read the analysis

      See the character count, emoji and caps warnings, spam-trigger words and a score out of 100 with tips.

    3. 3

      Check the inbox preview

      See where the line gets cut off in Gmail, Outlook and mobile, then adjust and copy it.

    Questions about the subject line tester

    How long should an email subject line be?
    Around 28 to 50 characters is a safe range. Past that it often gets cut off, especially on phones. The tester marks the point where each inbox truncates so you can see it.
    What counts as a spam-trigger word?
    Words and phrases that spam filters and readers associate with junk mail, like free, act now, guarantee, winner and rows of exclamation marks. The tester lists any it finds so you can swap them out.
    Is my subject line sent anywhere?
    No. The analysis runs in your browser and nothing is uploaded. Only your most recent subject is kept on this device so it is there when you come back.
    Does a high score guarantee opens?
    No tool can promise that. The score points you away from common mistakes. What gets opened still depends on your audience, your sender name and timing.

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