Bounce codes › Gmail
552 5.3.4: Your message exceeded Google's message size limits
The email is bigger than Gmail accepts. Attachments are the usual reason, but Gmail uses the same code for too many attachments and for headers that are too long.
Change the message Message is too big
The message, an attachment or a header is over Gmail’s size limit.
- Sent by: Gmail / Google Workspace
- Permanent (hard bounce). Sending the same message again fails again.
How Gmail words it (source):
Your message exceeded Google's message size limits.
Why it happens
- A large attachment. Attachments grow by about a third when they are packed into an email, so a file near the limit goes over it.
- Very many attachments in one message.
- Headers that are too large, for example hundreds of addresses in To or Cc, or a very long subject.
What to do
- Share big files as a link (Google Drive, OneDrive, Dropbox) instead of attaching them.
- Compress images and PDFs, or split the files over several emails.
- If the bounce mentions "header", put fewer addresses in To and Cc, or use Bcc or a mailing tool.
Don't confuse it with
552 5.2.2 is a full mailbox: there the recipient has no room at all. With 5.3.4 only this message is too big.
Questions
Is the address fine?
Yes. A smaller message will be delivered.
Hard or soft bounce?
The code is permanent for this message, but it says nothing bad about the address. Do not remove it.
Got a different bounce?
Paste the whole message into the bounce code lookup. It reads the code and the words and tells you whose move it is.