Email subject line insights
When an email subject line is too long
Long subject lines can get skimmed, truncated, or ignored before the email is opened.
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Keep the most important topic words early in the subject line and trim the setup. If the subject line has to carry several ideas at once, the reader is more likely to skim past it or miss the point entirely.
This may be why you're not getting opens. Vague or long subject lines are easy to skip.
Practical examples
Too long vs tighter subject lines
Too long
Following up on revised deck and stakeholder timeline for next week This is hard to scan and easy to truncate.
Tighter
Revised deck approval needed by Friday Same request, less setup.
Too long with extra context
Update on the client launch schedule, draft notes, and next steps for the team Too many ideas for a single preview line.
Shorter and specific
Client launch schedule update by Friday Short enough to read in one glance.
Common mistakes
Watch for these traps
Multiple topics
Trying to fit every detail into the subject line creates clutter.
Burying the ask
If the main request appears at the end, readers may never reach it.
Preview truncation
Long subject lines can get cut off before the useful part appears.
What works for subject lines
What works?
These subject lines get opened:
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Check your subject line before you send it
RepliStack's Subject Line Checker shows whether a long subject line is getting in the way of the open.
Related pages
Dive into related subject line insights
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