X.4.7 · Network and routing
SMTP enhanced status code 4.4.7
Delivery time expired
X.4.7 means the message expired: it sat in a queue longer than the allowed time without being delivered. The real cause is the earlier failure that kept it in the queue.
| Registry code | X.4.7 |
|---|---|
| Forms in use | 4.4.7, 5.4.7 |
| Registry name | Delivery time expired |
| Subject | 4: Network and routing |
| Permanent or temporary | 4.x.x persistent transient failure: retrying later may succeed; 5.x.x permanent failure: resending unchanged will not succeed |
| Associated basic codes | Not given |
| Defined in | [RFC 3463] |
What the registry says
The message was considered too old by the rejecting system, either because it remained on that host too long or because the time-to-live value specified by the sender of the message was exceeded. If possible, the code for the actual problem found when delivery was attempted should be returned rather than this code.
IANA SMTP Enhanced Status Codes registry, X.4.7
In practice
4.4.7 is the code people see when a message gave up after days of retries. The underlying cause is in the earlier deferrals: a server that never answered, a temporary block that never lifted, or a greylist that was never satisfied. Microsoft also uses 4.4.7 when a remote server's header limit or protocol timeout is reached. Read the last deferral reason in your logs.
What the sender should do
Look at the earlier deferrals in your logs, which name the actual problem. Persistent expiry to one domain often means the domain is unreachable or blocking you.
Would verifying the list have prevented 4.4.7?
Partly
The reply is not only about one address, but providers weigh how often a sender hits addresses that do not exist. Removing bad addresses before sending lowers that signal.
How providers use X.4.7
Quoted from each provider’s own error reference.
- Microsoft 365 4.4.7
Message expired
Common questions
- What does 4.4.7 mean?
- X.4.7 means the message expired: it sat in a queue longer than the allowed time without being delivered. The real cause is the earlier failure that kept it in the queue.
- What is the difference between 4.4.7 and 5.4.7?
- They share the subject and detail digits, so they report the same condition, "Delivery time expired". The first digit is the class: 4.x.x persistent transient failure: retrying later may succeed; 5.x.x permanent failure: resending unchanged will not succeed.
- What should I do about 4.4.7?
- Look at the earlier deferrals in your logs, which name the actual problem. Persistent expiry to one domain often means the domain is unreachable or blocking you.
- Would an email verifier have caught 4.4.7?
- Partly. The reply is not only about one address, but providers weigh how often a sender hits addresses that do not exist. Removing bad addresses before sending lowers that signal.
Full guides for this code
Sources
- IANA: SMTP Enhanced Status Codes registry (checked 2026-11-05)
- RFC 3463: Enhanced Mail System Status Codes (checked 2026-11-05)
- 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