SMTP 452 4.2.2
insufficient storage, mailbox full
SMTP 452 4.2.2 means the recipient's mailbox is over its storage quota, returned as a temporary failure so the sending server retries. Unlike the permanent 552 form, this one explicitly invites a later attempt, and mail often arrives once the recipient clears space.
Should you remove the address?
Suppress the address if it keeps failing
Not after one bounce. Keep it, let retries run, and suppress it only if it keeps coming back full across sends.
Soft bounce. Your sending server retries on its own. Investigate only if it keeps failing.
How it appears
452 4.2.2 Mailbox size limit exceeded
452 4.2.2 <[email protected]>: Recipient address rejected: mailbox full
452 4.2.2 Over quota
What causes it
- The recipient has exceeded their storage allocation.
- A shared or role mailbox has grown past its quota with nobody clearing it.
- The receiving server itself is low on disk and is deferring all mail.
How to fix it
In order — try the first one first.
- Allow the automatic retries to run — the address itself is valid.
- If it persists across weeks, suppress the address. A permanently full mailbox is abandoned, and abandoned mailboxes are what become recycled spam traps.
- If every recipient at one domain returns it, the problem is the server rather than the mailboxes, and there is nothing you can do from your side.
Who sends it
Gmail and Google Workspace use it for mailboxes that are out of storage but still active. Many other servers report a full mailbox the same way.
Gmail
Reply text The recipient's inbox is out of storage space.
Gmail asks the recipient to free up Google storage.
Common questions
- What does SMTP 452 4.2.2 mean?
- SMTP 452 4.2.2 means the recipient's mailbox is over its storage quota, returned as a temporary failure so the sending server retries. Unlike the permanent 552 form, this one explicitly invites a later attempt, and mail often arrives once the recipient clears space.
- Should I retry a 452 4.2.2 error?
- Yes, and your sending server does it automatically. 452 is a temporary deferral, and legitimate mail usually arrives on a retry within minutes or hours. Only investigate if it persists across many retries.
- How do I fix SMTP 452 4.2.2?
- Allow the automatic retries to run — the address itself is valid.
- Is 452 4.2.2 a hard bounce or a soft bounce?
- 452 4.2.2 is a soft bounce. It is temporary, and your sending server retries it automatically. Your sending server retries on its own. Investigate only if it keeps failing.
- Should I remove the address after a 452 4.2.2 bounce?
- Not after one bounce. Keep it, let retries run, and suppress it only if it keeps coming back full across sends.
- Will verifying my list prevent 452 4.2.2?
- Only partly. Temporary deferrals are not about the address, but providers defer senders whose mail looks risky, and a high rate of hard bounces is one of the signals they use.
Clean the list before the next send.
A bounce report only tells you about the addresses you already mailed. The rest of the list has the same kinds of dead mailboxes in it, and each one becomes a hard bounce recorded against your domain the moment you send.
- A real SMTP mailbox check on every row, before anything is sent
- Dead and mistyped addresses split out, so they never reach your sending tool
- Catch-all, disposable and role addresses flagged alongside
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Other 452 replies
Sources
- Source: Google Workspace Admin Help: Gmail SMTP errors and codes
- Source: RFC 3463: Enhanced Mail System Status Codes
Provider wording is quoted only where the provider publishes it.
Last reviewed 2026-10-22