Gmail content security rejection
Fix Gmail 552 5.7.0 message security block
Gmail uses 552 5.7.0 when message or attachment content presents a potential security issue. Review the actual files, archives, links, and sending account for compromise.
Gmail reports:
552 5.7.0 This message was blocked because its content presents a potential security issue.
The 5.x.x response is permanent for that content. Generate a safe new message rather than retrying unchanged.
What to investigate
- Blocked executable or script file types.
- Nested or password-protected archives.
- Malicious or compromised links.
- Unexpected attachments added by a compromised account or application.
- Gateway transformations that create prohibited content.
How to resolve it
- Verify the sender and attachment provenance.
- Scan and remove unsafe or prohibited content.
- Use an organization-approved sharing service for legitimate blocked files.
- Secure compromised accounts, tokens, and applications.
- Generate a clean new message and test with minimal content.
Frequently asked questions
What does Gmail 552 5.7.0 mean?
Gmail blocked the message because its content or attachments presented a potential security issue.
Will renaming a blocked attachment fix it?
No. Gmail can inspect archives and content; use a safe approved sharing method rather than disguising a prohibited file.
Is this a DNS authentication error?
No. SPF, DKIM, and DMARC changes do not make unsafe content acceptable.
Related email diagnostics
Primary source: Gmail SMTP errors and codes.