SMTP recipient mailbox error
SMTP 552 5.2.2: Mailbox full
The recipient mailbox has reached its storage or administrative quota. The recipient or their email administrator must make space.
The registered response text is:
552 5.2.2 Mailbox full
The 552 reply rejects this attempt, but the condition can clear after storage becomes available.
What to do
- Check that the rejected recipient address is correct.
- Contact the recipient through another channel.
- Ask them to free storage or contact their email administrator.
- Send a new message after they confirm that space is available.
Avoid rapid retries. If the address repeatedly returns permanent mailbox errors after the quota is fixed, ask the recipient’s provider to inspect the account.
Frequently asked questions
Who can fix SMTP 552 5.2.2?
The recipient can delete mail, or their email administrator can increase the mailbox quota.
Should I change SPF, DKIM, or DMARC?
No. Sender authentication cannot create space in a recipient mailbox.
Related email diagnostics
Gmail 550 5.1.1: The email account that you tried to reach does not existResolve Gmail 550 5.1.1 by verifying the recipient address, account status, aliases, and recent mailbox changes.
SMTP 5.3.4: Message too big for systemFix SMTP 5.3.4 when a message exceeds the receiving system's size limit by reducing attachments or using a file link.
Primary sources: IANA SMTP Enhanced Status Codes, RFC 3463: Enhanced Mail System Status Codes.