5.7.233 Tenant exceeded its daily limit for sending email to external recipients
5.7.233 Tenant exceeded its daily limit for sending email to external recipients
The ceiling here is on external recipients specifically, so internal mail keeps working while everything leaving the organisation stops. That split is the useful diagnostic: if a scanner can still mail colleagues but not customers, this is the reason, and it is not the device.
Check it from the machine that is failing
npx zerosmtp-check --explain "5.7.233 Tenant exceeded its daily limit for sending email to external recipients"
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, and not your credentials
Authentication succeeded. The message was accepted and then refused on volume: the tenant has sent more in the last 24 hours than its limit allows. Changing SMTP settings does nothing here, and re-enabling SMTP AUTH does nothing either.
- Find what is sending. A device stuck in a retry loop can spend a tenant’s daily allowance overnight without anybody noticing.
- Check whether the send is a burst or a new steady rate. A burst waits; a steady rate over the limit needs a different route.
- Limits reset on a rolling 24-hour window, not at midnight, so sending resumes gradually rather than all at once.
Worth saying plainly because it is easy to sell against: this is not a problem a relay fixes by itself. If the volume genuinely exceeds what the tenant may send, it exceeds what this project allows too - 200 messages a day, and no paid tier lifts it.
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 23 Aug 2026