An email 552 error is a permanent bounce that usually means one of two things: the message is larger than the receiving server accepts ("552 5.3.4 Message size exceeds fixed limit"), or the recipient's mailbox has run out of storage ("552 5.2.2 Mailbox full / Requested mail action aborted: exceeded storage allocation"). The bounce text tells you which.
Before you start
- Open the bounce and find the line with
552. - Check the total size of the email including attachments.
Message too large
Attachments grow by about a third when encoded for email, so a 20 MB file becomes roughly 27 MB. Many providers reject messages above around 20–25 MB, and some business servers use lower limits.
- Compress or resize files: zip documents, export smaller PDFs, resize photos.
- Split attachments across several emails.
- Share a link instead: upload the file to cloud storage, or to a folder on your hosting via cPanel → File Manager, and email the download link.
Recipient mailbox full
- If the bounce mentions storage or quota for the recipient, only they can fix it. Contact them another way.
- If it is your own mailbox rejecting incoming mail, raise its quota in cPanel → Email → Email Accounts → Manage or delete old mail. See mailbox quota full.
- If the whole account is out of space, every mailbox is affected; see cPanel disk space full.
Note: Some servers still use the older code 452 for a temporarily full mailbox. That is retried automatically; 552 is not.
What to check afterwards
Resend the smaller message or link, and check cPanel → Email → Track Delivery shows it accepted by the remote server.
FAQ
What is the maximum attachment size I can send?
It depends on both your server and the recipient's. Keeping messages under about 20 MB is a safe rule.
Why did a 15 MB file bounce?
Encoding overhead pushed it over the recipient's limit, or their limit is lower.
Can I raise the recipient's limit?
No, only their mail administrator can.