Subject Line Tester

See exactly where the inbox cuts your subject off — phones show about 35 characters, desktops about 60 — and catch the merge tag you forgot to replace before ten thousand people read “Hi [FIRST_NAME]”.

Runs in your browser — nothing is uploaded No sign-up
35 — phone 60 — desktop
0 characters 0 words

The subject is the easy half

Presend checks the whole message in your compose window — leaked keys, missing attachments, AI phrasing, tone — and holds the send when something looks wrong.

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