Gmail 451 4.4.2
Timeout, closing connection
Gmail 451 4.4.2 means: timeout, closing connection. It is a temporary failure, so your server retries it. The connection timed out. Let the queue retry and check for network problems or a slow sending client.
Gmail’s exact wording
Quoted from Google Workspace Admin Help: Gmail SMTP errors and codes, checked 2026-11-05. Placeholders are Gmail’s own.
Reply text
Timeout - closing connection. For more information, go to About SMTP error messages.
| Who sends it | Gmail and Google Workspace |
|---|---|
| Basic code | 451: Requested action aborted: local error in processing (RFC) |
| Enhanced code | 4.4.2: Bad connection |
| Permanent or temporary | Temporary (4xx) |
| Verifying the list prevents it | No |
What the sender should do
The connection timed out. Let the queue retry and check for network problems or a slow sending client.
Would verifying the list have prevented Gmail 451 4.4.2?
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 Gmail 451 4.4.2 mean?
- Gmail 451 4.4.2 means: timeout, closing connection. It is a temporary failure, so your server retries it. The connection timed out. Let the queue retry and check for network problems or a slow sending client.
- Should I retry after Gmail 451 4.4.2?
- 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 Gmail 451 4.4.2?
- 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.
The same code elsewhere
Sources
- Google Workspace Admin Help: Gmail SMTP errors and codes (checked 2026-11-05)
- IANA: SMTP Enhanced Status Codes registry (checked 2026-11-05)
- RFC 5321: Simple Mail Transfer Protocol, section 4.2.3 (reply codes) (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