Gmail 552 5.3.4
Message, attachment or header too large
Gmail 552 5.3.4 means: message, attachment or header too large. It is a permanent failure, so do not retry it unchanged. The message exceeded one of Google's size limits: total size, number of attachments, header size or a single header. Reduce the size or share files as links.
Gmail’s exact wording
Quoted from Google Workspace Admin Help: Gmail SMTP errors and codes, checked 2026-11-05. Placeholders are Gmail’s own.
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Your message exceeded Google's message size limits. To view our message size guidelines, go to Send attachments with your Gmail message.
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The number of attachments (num-attachments) exceeds Google's limit of limit attachments. To view our attachment size guidelines, go to Gmail receiving limits in Google Workspace.
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The size of your message (size bytes) exceeded Google's message size limits of limit bytes. To view our message size guidelines, go to Gmail receiving limits in Google Workspace.
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Your message exceeded Google's message header size limits. To view our header size guidelines, go to Gmail message header limits.
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Your message exceeded Google's message header size limits. Messages must not exceed limit total header bytes or limit header fields. To view our header size guidelines, go to Gmail message header limits.
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The size of the header name header value (size bytes) exceeds Google's limit of limit bytes per individual header size. To view our header size guidelines, go to Gmail message header limits.
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The size of one of the header values (size bytes) exceeds Google's limit of limit bytes per individual header size. To view our header size guidelines, go to Gmail message header limits.
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The size of a header name (size bytes) exceeds Google's header name limit of limit bytes. To view our header size guidelines, go to Gmail message header limits.
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Your message has a Subject: header that exceeds Google's message header size limits. To view our header size guidelines, go to Gmail message header limits.
| Who sends it | Gmail and Google Workspace |
|---|---|
| Basic code | 552: Requested mail action aborted: exceeded storage allocation (RFC) |
| Enhanced code | 5.3.4: Message too big for system |
| Permanent or temporary | Permanent (5xx) |
| Verifying the list prevents it | No |
In practice
Gmail lists nine size-related versions of 552 5.3.4: the whole message, the number of attachments, the total header size, the number of header fields, one header's value, one header's name, and the Subject line. The reply usually includes the actual size and Google's limit. Large attachments are the common cause, but long tracking headers or very long subjects from marketing tools can trigger the header versions.
What the sender should do
The message exceeded one of Google's size limits: total size, number of attachments, header size or a single header. Reduce the size or share files as links.
Would verifying the list have prevented Gmail 552 5.3.4?
No
This reply is about your sending setup, the message or the receiving system, not about whether the address exists, so verifying the list will not prevent it.
Common questions
- What does Gmail 552 5.3.4 mean?
- Gmail 552 5.3.4 means: message, attachment or header too large. It is a permanent failure, so do not retry it unchanged. The message exceeded one of Google's size limits: total size, number of attachments, header size or a single header. Reduce the size or share files as links.
- Should I retry after Gmail 552 5.3.4?
- No. It is a permanent (5xx) failure, so the same message to the same address will fail again. Fix the cause first. The message exceeded one of Google's size limits: total size, number of attachments, header size or a single header. Reduce the size or share files as links.
- Would verifying my list have prevented Gmail 552 5.3.4?
- No. This reply is about your sending setup, the message or the receiving system, not about whether the address exists, so verifying the list will not prevent it.
The same code elsewhere
Sources
- Google Workspace Admin Help: Gmail SMTP errors and codes (checked 2026-11-05)
- IANA: SMTP Enhanced Status Codes registry (checked 2026-11-05)
- RFC 5321: Simple Mail Transfer Protocol, section 4.2.3 (reply codes) (checked 2026-11-05)
Registry and provider wording is quoted exactly; guidance is written by the SimpleVerifier Team.
SimpleVerifier Team · Last checked against the sources 2026-11-05