4.4.7 is a permanent SMTP reply meaning message expired. Microsoft explains that the sending server tried to relay or deliver the message but did not finish before the expiration time. It can also mean a header limit was reached on the remote server, or another protocol timeout happened. It usually points to a problem at the receiving server.
What 4.4.7 means
Microsoft explains that the sending server tried to relay or deliver the message but did not finish before the expiration time. It can also mean a header limit was reached on the remote server, or another protocol timeout happened. It usually points to a problem at the receiving server.
Common causes
The receiving server was down or unreachable
Most commonIts MX hosts did not answer, or a firewall blocked the connection, for the whole retry period.
The receiver kept deferring you
CommonRepeated 4xx answers (rate limits, greylisting, reputation deferrals) until the message expired.
DNS or MX records for the recipient domain are wrong
CommonMX points to a host that does not accept mail, so every attempt fails.
How to fix 4.4.7
- 1
Check the recipient domain
Run an MX lookup on the recipient domain to confirm its mail servers exist and resolve.
- 2
Look at the earlier deferrals
Your server logs show the 4xx answers before expiry. They name the real reason, such as a rate limit or reputation deferral.
- 3
Reduce recipients per message
Microsoft suggests fewer recipients in the header when this error is tied to one host.
Confirm your domain is set up correctly
Most delivery failures — permanent or temporary — trace back to authentication or reputation. Run a free EmailHealth check to confirm SPF, DKIM, DMARC, blacklist status, and TLS are all healthy for your sending domain. If you send in volume, free daily monitoring will alert you before a small issue becomes a flood of bounces.