Microsoft 365 5.7.233
Your message can't be sent because your tenant exceeded its daily limit for sending email to external recipients (tenant external recipient rate limit)
Microsoft 365 5.7.233 means: your message can't be sent because your tenant exceeded its daily limit for sending email to external recipients (tenant external recipient rate limit). It is a permanent failure, so do not retry it unchanged. The fix is in the sending or receiving configuration named above, not in the list. Fix that, then resend.
Microsoft 365’s exact wording
Quoted from Microsoft Learn: Email non-delivery reports and SMTP errors in Exchange Online, checked 2026-11-05. Placeholders are Microsoft 365’s own.
Provider's description
Your message can't be sent because your tenant exceeded its daily limit for sending email to external recipients (tenant external recipient rate limit)
Possible cause
The number of external recipients emailed in a 24-hour period exceeds the external recipient rate limit in Exchange Online. The limit applies per tenant.
Provider's advice
The external recipient rate limit is tracked over a 24-hour rolling window. When the count for the most recent 24-hour period falls below the limit, users in the tenant can resume sending messages to external recipients. The limit helps prevent the distribution of unsolicited bulk messages.
| Who sends it | Microsoft 365, Exchange Online and Outlook.com |
|---|---|
| Basic code | Microsoft 365 lists the enhanced code only |
| Enhanced code | 5.7.233: Microsoft 365-specific, not in the IANA registry. Its subject digit puts it under 5.7.0 other or undefined security status. |
| Permanent or temporary | Permanent (5xx) |
| Verifying the list prevents it | No |
In practice
This tenant-wide external recipient rate limit is separate from per-mailbox limits. If you reach it, look for compromised accounts first, then consider a dedicated sending service for bulk mail. The limit is counted on a rolling 24-hour window. Mail to internal recipients keeps flowing while the external limit is reached.
What the sender should do
The fix is in the sending or receiving configuration named above, not in the list. Fix that, then resend.
Would verifying the list have prevented Microsoft 365 5.7.233?
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 Microsoft 365 5.7.233 mean?
- Microsoft 365 5.7.233 means: your message can't be sent because your tenant exceeded its daily limit for sending email to external recipients (tenant external recipient rate limit). It is a permanent failure, so do not retry it unchanged. The fix is in the sending or receiving configuration named above, not in the list. Fix that, then resend.
- Should I retry after Microsoft 365 5.7.233?
- No. It is a permanent (5xx) failure, so the same message to the same address will fail again. Fix the cause first. The fix is in the sending or receiving configuration named above, not in the list. Fix that, then resend.
- Would verifying my list have prevented Microsoft 365 5.7.233?
- 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.
Sources
- 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