Gmail delivery response
Gmail 552 5.3.4: Your message exceeded Google's message size limits
Gmail rejected the message because the full message, its attachments, or its headers exceeded a Google limit. The rest of the response states which limit was exceeded.
A representative response is:
552 5.3.4 Your message exceeded Google's message size limits.
Treat this as permanent until the complete provider response and retry behavior show otherwise.
Read the complete response
Gmail can name total message size, attachment count, total header bytes, header count, or one oversized header. Fix the limit that Gmail names.
How to fix it
- Save the complete response and raw message.
- Measure the encoded message, not only the original files; MIME and base64 increase size.
- Remove attachments or share large files by link.
- If Gmail names headers, remove duplicated or oversized generated headers.
- Build and send a new, smaller message.
MailFixIt scope
This is a message-construction problem, not a sender DNS problem. MailFixIt cannot reduce the message or its headers.
Frequently asked questions
What does Gmail 552 5.3.4 mean?
The message, attachment count, or header data exceeded a Google size limit.
Can MailFixIt prove this entire bounce from public DNS?
No. The current checker can evaluate selected public DNS configuration, but it cannot recreate recipient state, credentials, reputation, message content, or a historical provider SMTP decision.
Related email diagnostics
Primary sources: Gmail SMTP errors and codes, Google email sender guidelines.