Microsoft 365 4.4.316
Connection refused [Message=Socket error code 10061]
Microsoft 365 4.4.316 means: connection refused [Message=Socket error code 10061]. It is a temporary failure, so your server retries it. The fix is in the sending or receiving configuration named above, not in the list. Fix that, then resend.
Microsoft 365’s exact wording
Quoted from Microsoft Learn: Email non-delivery reports and SMTP errors in Exchange Online, checked 2026-11-05. Placeholders are Microsoft 365’s own.
Provider's description
Connection refused [Message=Socket error code 10061]
Possible cause
Microsoft 365 or Office 365 is trying to send a message to an email server outside Microsoft 365 or Office 365, but all attempts to connect are failing because of a network connection issue at the external server's location.
Provider's advice
This error almost always indicates an issue that affects the receiving server or network outside of Microsoft 365 or Office 365. The error should also include the IP address of the server or service that's generating the error. You can use this address to identify the party that's responsible for fixing this issue.
| Who sends it | Microsoft 365, Exchange Online and Outlook.com |
|---|---|
| Basic code | Microsoft 365 lists the enhanced code only |
| Enhanced code | 4.4.316: Microsoft 365-specific, not in the IANA registry. Its subject digit puts it under 5.4.0 other or undefined network or routing status. |
| Permanent or temporary | Temporary (4xx) |
| Verifying the list prevents it | No |
In practice
4.4.316 Connection refused means Microsoft 365 could not connect to the external mail server at all, because of a network problem at the destination: a firewall, a server that is down, or an MX record pointing at the wrong place. The fix is on the receiving side. Test the connection to the recipient's MX on port 25 from outside their network.
What the sender should do
The fix is in the sending or receiving configuration named above, not in the list. Fix that, then resend.
Would verifying the list have prevented Microsoft 365 4.4.316?
No
This reply is about your sending setup, the message or the receiving system, not about whether the address exists, so verifying the list will not prevent it.
Common questions
- What does Microsoft 365 4.4.316 mean?
- Microsoft 365 4.4.316 means: connection refused [Message=Socket error code 10061]. It is a temporary failure, so your server retries it. The fix is in the sending or receiving configuration named above, not in the list. Fix that, then resend.
- Should I retry after Microsoft 365 4.4.316?
- Your sending server retries it automatically, because it is a temporary (4xx) failure. Investigate only if it keeps coming back over several hours.
- Would verifying my list have prevented Microsoft 365 4.4.316?
- No. This reply is about your sending setup, the message or the receiving system, not about whether the address exists, so verifying the list will not prevent it.
Sources
- Microsoft Learn: Email non-delivery reports and SMTP errors in Exchange Online (checked 2026-11-05)
Registry and provider wording is quoted exactly; guidance is written by the SimpleVerifier Team.
SimpleVerifier Team · Last checked against the sources 2026-11-05