552 5.2.2 — Mailbox full / over quota
The recipient address is the problem
SMTP error 552 5.2.2 means the recipient mailbox has no storage left. Despite the 5.x prefix it behaves as a temporary condition - the address is real and the owner can free space - so it should be treated as a soft bounce and retried, not permanently suppressed.
What the server actually says
552 5.2.2 The email account that you tried to reach is over quota. Please direct
the recipient to https://support.google.com/mail/?p=OverQuotaPerm - gsmtpWhat you see
One address fails repeatedly over days while everything else delivers. Often an abandoned-but-not-deleted mailbox.
Why it happens
- The recipient genuinely has no storage left.
- The mailbox is abandoned - nobody is clearing it, so it will stay full indefinitely.
- An organisation-wide quota was reduced, filling many mailboxes at once.
How to fix it
- Treat it as a soft bounce and retry later. The address is valid. Space may be freed, so a retry over the following days can deliver.
- Cap the number of retries. An abandoned mailbox stays full forever. After several failures across several days, stop - it is functionally dead even though the address resolves.
- Keep it out of your hard-bounce metric. Counting over-quota as a hard bounce inflates the number providers judge you on and can trigger filtering you did not earn.
What not to do
- Do not permanently suppress on the first occurrence. The address exists and may well accept mail next week.
- Do not retry forever either. An abandoned full mailbox never clears, and endless retries waste send capacity and inflate failure counts.
- Do not treat it as a reputation signal. Your sending identity is not being judged here.
Frequently asked questions
Why is a 5.x code a soft bounce?
The numbering is inconsistent across providers. The condition - no storage - is inherently temporary, so the practical classification is soft regardless of the 5.x prefix.
How many times should I retry?
A handful of attempts spread over several days. If it is still full after that, the mailbox is abandoned and should be dropped.
How MailPilot helps
MailPilot classifies this error automatically on every connected mailbox and tells you which side is at fault, so a throttle is never mistaken for a dead recipient and a credential failure never suppresses a healthy address. It also monitors real inbox placement and checks SPF, DKIM and DMARC on every mailbox, which is where most policy rejections start.
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Last reviewed 2026-10-11 by the MailPilot team.