5.3.5: receiving system misconfigured
The receiving system's own configuration does not allow it to accept this message, a problem only its administrator can fix.
- Standard
- Provider
- Permanent (5xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 5.3.5
- 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
- The recipient's side. Their mail admin has to change something; you can tell them.
- What the server says
5.3.5 System incorrectly configured
What it means
X.3.5 is the receiver admitting a setup problem: its configuration does not permit it to take the message, for example a domain it is meant to handle but is not set up for, or a delivery path that leads nowhere. RFC 3463 ties it to no class. 5.3.5 means the message was returned; 4.3.5 means the server expects the problem to be fixed and will accept a retry. Senders can only check that they used the right address and that the recipient domain's MX records point where they should.
Common causes
- A server listed as a domain's mail exchanger that is not configured to accept that domain.
- A broken delivery or routing rule on the receiving side.
- A recent migration that left the old or the new server half set up.
How to fix it
- 01Check the recipient address and the domain's MX records.
- 02Send the full bounce to the recipient or to their postmaster address.
- 03Recipient admins: check that the server accepts the domain, and review recent configuration changes.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
Related codes
- 5.3.0Receiving system problem, unspecified.The receiving server normally accepts mail, but a problem on that system itself, rather than with the mailbox or the message, stopped this delivery.
- 5.4.6Mail routing loop.The message was passed back and forth between servers, or forwarded around a circle, until a server noticed the loop and stopped it.
- 5.4.4No route to the recipient domain.The mail system could not work out where to send the message next, because DNS gave no usable mail server for the recipient domain.
Further reading
All 105 standard codesEvery code in the wikiPaste your own bounce