5.2.2: the mailbox is full
By Jose Pollman · Published · Updated
Treat 5.2.2 as a soft bounce. The recipient is over their storage quota, and although the 5.x.x prefix says permanent, a full mailbox is usually temporary; some servers report the same condition as 4.2.2. Retry for a few days rather than suppressing on the first bounce, and stop sending only if it persists for a week or more.
The error
552 5.2.2 Over quota
550 5.2.2 The recipient's inbox is out of storage spaceWhat it means
The recipient is over quota. The 5.x.x prefix says permanent, but a full mailbox is usually temporary — treat it as soft until it repeats.
Nothing is wrong at your end. The recipient or their mail provider has to act, and there is usually nothing you can do but stop sending.
Why it happens
Receivers are inconsistent here: the same condition is 4.2.2 on some systems and 5.2.2 on others. Suppressing on the first 5.2.2 loses real subscribers, so the sensible policy is to retry and only suppress after it persists.
How to fix it
- Retry for a few days rather than suppressing immediately.
- If it persists for a week or more, the mailbox is abandoned — stop sending.
Related guides
- 421: service not available — The receiving server is not accepting mail right now — overloaded, in maintenance, or deliberately throttling you.
- TLS and DANE validation bounces — Microsoft would not deliver because the destination’s TLS setup failed validation — no STARTTLS, an expired certificate, a hostname mismatch, or a failing DANE or DNSSEC record.
- 4.7.0: temporarily refused on policy grounds — The receiver is temporarily refusing your mail for policy reasons — most often rate limiting, greylisting, or a TLS requirement that was not met.