Diagnose an email that did not arrive
Work from the bounce message outwards. Most cases are answered in two minutes.
Start with the evidence rather than the theory. A bounce message says what happened; guessing does not.
Was there a bounce?
Read the status code in the bounce. It tells you who rejected the message and why.
| Code | Meaning | Do |
|---|---|---|
| 550 5.1.1 | No such mailbox | Check the spelling of the address |
| 550 5.7.1 | Rejected by policy | Usually SPF, DKIM or DMARC. Check the records |
| 552 / 5.2.2 | Mailbox full | Recipient must clear space |
| 421 / 4.x.x | Temporary | Nothing. The sender retries automatically |
No bounce at all
- Check the spam folder, both ends
And any rule that files mail into a folder nobody opens.
- Confirm the MX record
dig example.com MX +shortmust show your provider. A stale MX sends mail to the old host, where it sits. - Look at the provider log
Workspace and 365 both have message trace. It shows whether the message arrived and what was done with it.
- Send a test from outside
From a personal address on another provider, so you are testing the real path.
Send us the full bounce message including headers, the exact sender and recipient, and the time with the timezone. With those three, most cases are answered on the first reply.