Permanent failure — do not retry
SMTP 552 5.2.2
mailbox full
SMTP 552 5.2.2 means the recipient's mailbox is over its storage quota and the server will not accept the message. Although it is a 5xx permanent code, the cause is usually temporary in practice — the mailbox is real and will accept mail again once the recipient clears space.
How it appears
552 5.2.2 Requested mail action aborted: exceeded storage allocation
552 5.2.2 <user@example.com>: Recipient address rejected: mailbox full
What causes it
- The recipient has exceeded their storage quota and has not cleared it.
- The mailbox is abandoned and filling with mail nobody reads.
- A shared or role mailbox has grown past its allocation.
How to fix it
In order — try the first one first.
- Retry later rather than deleting immediately — the address itself is valid.
- If it persists for weeks, treat it as abandoned and remove it. A permanently full mailbox is functionally a dead address, and often an early sign of a recycled spam trap.
- Do not keep hammering it. Some providers escalate a repeatedly refused message to a reputation signal.
Common questions
- What does SMTP 552 5.2.2 mean?
- SMTP 552 5.2.2 means the recipient's mailbox is over its storage quota and the server will not accept the message. Although it is a 5xx permanent code, the cause is usually temporary in practice — the mailbox is real and will accept mail again once the recipient clears space.
- Should I retry a 552 5.2.2 error?
- No. 552 is a permanent failure, so the message will never be delivered no matter how many times you try. Remove the address — repeated sends to permanent failures are one of the main signals mailbox providers use to throttle a sender.
- How do I fix SMTP 552 5.2.2?
- Retry later rather than deleting immediately — the address itself is valid.
Last reviewed 2026-09-11