552 5.7.0 Message Blocked — Content Presents a Potential Security Issue (Gmail)

What’s actually happening

An email bounces the instant you send it with 552 5.7.0, and the link points at Gmail's blocked-attachment guidelines. Gmail blocks certain executable file types regardless of intent — and zipping or renaming them doesn't get past it, because it inspects inside archives. The same code also fires when Gmail's virus scanner flags the payload. This is content-based, not a reputation or quota problem, so other mail from the same account still sends fine.

Common causes

• An attachment is a blocked executable type — .exe, .js, .jar, .scr, .bat, .cmd, .msi, .vbs, and similar
• The blocked file is inside a .zip, .rar, .7z, or other archive — Gmail looks inside compressed files
• A document with active macros or embedded executable content tripped the security filter
• Gmail's virus scan detected malware or a suspicious signature in the message or attachment
• A password-protected archive Gmail can't scan, which it treats as a potential risk

How to fix it

1. Share the file via a link insteadUpload to Google Drive, Dropbox, or similar and send the link. This is the standard workaround for legitimate executables — the message carries no blocked attachment, so it passes.
2. Don't bother zipping or renamingGmail inspects archive contents and isn't fooled by a changed extension. A .exe renamed to .txt or stuffed in a .zip still gets blocked. Skip this dead end.
3. Confirm the file is actually cleanBefore forcing it through, scan the attachment with antivirus. A 552 from the virus scanner can be a true positive — don't assume it's a false alarm.
4. Repackage the content in an allowed formatIf you're sending code or scripts, paste them inline, attach as .txt, or use a source format Gmail permits. For installers, a signed download link is cleaner than fighting the filter.
5. Use Drive sharing for recurring transfersIf you routinely send blocked types to the same people, standardize on a shared Drive folder or file host. It sidesteps the filter every time instead of bouncing per message.