530 5.7.1 Delivery not authorized
530 5.7.1 Delivery not authorized
Authentication is required and was not completed, or the authenticated account is not allowed to send as the address in the From field. The reply code 530 is the useful part and Microsoft does document it for this one: 530 is sent before the message body is accepted, so the refusal happened at the envelope rather than over the content.
Check it from the machine that is failing
npx zerosmtp-check --explain "530 5.7.1 Delivery not authorized"
No install and nothing sent. It reads the refusal your own client printed - which is rarely what the server said, because libraries and device panels rewrite it - and says which of these cases you are in.
If the send is hanging rather than being refused, the cause is usually the network and not the credentials. npx zerosmtp-check with no arguments checks ports 25, 587 and 465 from where you are standing.
This is not the Basic auth shutdown
Authentication worked. Do not change the authentication settings — the problem is the From address.
- Check what address the device or application puts in
From. - Check which mailbox the credentials belong to.
- If they differ, either set
Fromto the authenticated mailbox, or grant that mailbox Send As on the address you want to use.
This turns up most often after pointing a device at a shared or service mailbox and leaving the old From address in its settings.
Two things this is often confused with
| Symptom | Actual cause |
|---|---|
| Connection times out; no authentication error ever appears | The network is blocking outbound SMTP. Cloud providers block port 25 and often 587 by default — see troubleshooting. |
Certificate verify failed / unable to get local issuer certificate | The device’s trust store cannot validate the server certificate. Common on firmware predating current root CAs — see the Canon Maxify MB2755 case. |
Source: Microsoft’s own list of Exchange Online error codes. This entry was written from that documentation rather than from watching a machine fail, which is worth knowing when you compare it against what your hardware actually printed.
Related
- All SMTP AUTH error messages
- Which devices have OAuth firmware
- What breaks at the end of December 2026
Seeing a string that is not here? Report it with what produced it. Errors from real hardware are worth more than anything transcribed from documentation.
Last reviewed 2026-08-16.
Updated 22 Aug 2026