552 5.2.2: Mailbox full, or submission quota exceeded
5.2.2 means two different things. From Gmail, the recipient’s inbox is out of storage (452 4.2.2 is the temporary form). From Microsoft 365, it means you exceeded your own sending limit: the recipient or message rate limit on your account. Read the text to tell which side has the problem.
The exact messages
Gmail / Google Workspace
552 5.2.2 The recipient's inbox is out of storage space and inactive.
Gmail / Google Workspace
452 4.2.2 The recipient's inbox is out of storage space.
Microsoft 365 / Exchange Online
5.2.2 Submission quota exceeded
Any mail server (RFC standard meaning)
5.2.2 Mailbox full
Why it happens
- Gmail: the recipient’s storage is full, often an abandoned account.
- Microsoft: your account exceeded Exchange Online’s recipient or message rate limits.
- Microsoft: a compromised account sending spam can also trip this.
How to fix it
- Gmail full mailbox: remove the address from your list; full and inactive inboxes rarely come back.
- Microsoft quota: wait for the rolling window to clear and lower per-mailbox volume.
- If you did not send that volume, treat the account as compromised.
If you send cold email
A full, inactive Gmail inbox is a sign of a dead address; suppress it. A Microsoft quota bounce means one mailbox is carrying too much volume.
How WarmHawk handles it
WarmHawk never sends more than a mailbox’s own daily cap, spaces sends from one mailbox at least 8 minutes apart with random jitter, and starts a newly warmed mailbox at 5 campaign emails a day, growing 20% a day. A temporary failure is retried with backoff (30 minutes, then doubling) and the lead is suppressed after 4 attempts, so a throttled mailbox is never hammered. How WarmHawk works →
Related bounce codes
- 5.1.90Daily recipient limit reached
- 5.2.1Recipient account inactive or disabled
- 5.1.8Access denied, bad outbound sender
Sources, checked 2026-09-29: Google Workspace: Gmail SMTP errors and codes · Microsoft Learn: NDRs and SMTP errors in Exchange Online · Microsoft Learn: Exchange Online sending limits · RFC 3463: Enhanced Mail System Status Codes. Have a different bounce? Paste it into the decoder →
Questions
5.2.2 questions
What does 5.2.2 mean?+
5.2.2 means two different things. From Gmail, the recipient’s inbox is out of storage (452 4.2.2 is the temporary form). From Microsoft 365, it means you exceeded your own sending limit: the recipient or message rate limit on your account. Read the text to tell which side has the problem.
Is 5.2.2 a temporary or permanent error?+
Both forms exist. A reply starting with 4 (such as 4.2.2) is temporary, and the sending server will retry; a reply starting with 5 is permanent, and the message will not be retried until you fix the cause.
How do I fix 5.2.2?+
Gmail full mailbox: remove the address from your list; full and inactive inboxes rarely come back. Microsoft quota: wait for the rolling window to clear and lower per-mailbox volume. If you did not send that volume, treat the account as compromised.