5.3.2: server not accepting mail
The server holding the mailbox is not accepting messages at all, because it is shutting down, overloaded, in maintenance, or set never to receive mail.
- Standard
- Provider
- Permanent (5xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 5.3.2
- Provider
- Standard SMTP codes
- Temporary or permanent
- PermanentRefused for good: the message comes back to the sender, and resending it gets the same answer.
- Who has to act
- Either side, depending on the cause. Start with the checks below that are yours.
- What the server says
5.3.2 System not accepting network messages
What it means
RFC 3463 gives imminent shutdown, excessive load and maintenance as examples, and says X.3.2 can be permanent or temporary. The temporary form, 4.3.2, is the usual one during restarts and maintenance windows, and the sending server simply retries. The permanent form, 5.3.2, fits a host that never accepts mail: RFC 7504 added reply code 521 for exactly that case, and the registry pairs 521 with X.3.2. So 4.3.2 asks for patience, while 5.3.2 tells you this host is the wrong place to send to, which usually points to DNS: an MX or address record aimed at a server that does not take mail.
Common causes
- The receiving server is restarting, being upgraded or in maintenance.
- The server is overloaded and refusing new messages for now.
- An MX record points to a host that is not set up to receive mail.
How to fix it
- 01For 4.3.2, let the sending server retry.
- 02For 5.3.2, look up the recipient domain's MX records and check that they name a real mail server.
- 03If the domain is yours, point its MX records at the server that actually handles your mail.
- 04If it persists, contact the recipient's administrator with the full bounce.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
Related codes
- 521Host does not accept mail.The server answered the connection only to say that it never accepts mail, so delivery to this host cannot work.
- 421Service not available.The receiving server is closing the connection and will not take mail right now. The reply is temporary, so the sending server keeps the message and tries again later.
- 4.3.1Receiving system out of storage.The receiving mail server has run out of storage space, so it cannot accept messages for now; the sending server keeps the message and retries later.
- 4.4.1No answer from the receiving server.The sending server tried to connect to the receiving server and got no answer, so it keeps the message and tries again later.
Further reading
All 105 standard codesEvery code in the wikiPaste your own bounce