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Gmail 552 5.7.0: blocked for a potential security issue

552 5.7.0Message blocked for a potential security issuePermanent: retrying will not helpFrom Gmail and Google Workspace

Example
552-5.7.0 This message was blocked because its content presents a potential security issue. Please visit https://support.google.com/mail/?p=BlockedMessage to review our message content and attachment content guidelines. - gsmtp

What it means

Gmail scans attachments and links for malware and for file types it never accepts. When it finds one, it rejects the message with this 5.7.0 response. The verdict is about the payload, not the sender; the same server can send other mail to Gmail normally.

Gmail refuses executable formats such as .exe, .bat, .js, .msi, and .scr, including those hidden inside zip or other archives, and it blocks password-protected archives containing them. Documents with malicious macros also trigger it. The rejection is permanent, so resending the same file will fail.

Likely causes

  • An attached executable or script, even renamed or zipped.
  • An encrypted archive that Gmail cannot inspect, where the file names suggest executables.
  • An Office document with macros that match known malware patterns.
  • A genuinely infected file sent unknowingly from a compromised machine.

How to fix it

  1. Scan the attachment with up-to-date antivirus before anything else.
  2. Share software or scripts through a file share or code repository, then send the link.
  3. If it must be email, remove macros or save the document in a format without active content, such as PDF.
  4. Do not try to bypass the filter with renamed extensions; Gmail checks file contents, and repeated attempts look like malware delivery.

Checks that apply

  • Email Header Analyzer Shows the message path, which helps confirm whether the attachment came from your system or was added by a relay.
  • Blacklist Check If you suspect infection, checks whether your sending IP is listed for malware distribution.
See the example diagnosed

The classification runs without network lookups and we never store your paste.

FAQ

Can a Workspace admin allow the file type?
No. Google’s blocked executable types cannot be allowed by admins, though admins can add stricter rules.
Does Gmail block every zip file?
No. Archives are fine unless they contain blocked file types or cannot be scanned and look risky.

Google Postmaster Tools Google email sender guidelines

All 191 bounce codes