5.7.233: tenant reached its external recipient limit

What it means

The tenant external recipient rate limit caps how many recipients outside the tenant's accepted domains its users together can send to in a rolling 24 hours. The cap depends on how many licenses the tenant has, and group members are counted one by one after expansion. Once it is reached, external mail bounces with 5.7.233 for users across the tenant, while internal mail continues. Sending to outside recipients resumes when the 24-hour total falls below the limit. Admins can see their limit in the Tenant Outbound External Recipients report.

Common causes

• The tenant's users together sent to more external recipients than its licenses allow per day.
• A message to a distribution group with many external members was counted member by member.
• A compromised account sent a spam run.

How to fix it

1. 01Wait for the rolling 24-hour total to drop below the limit.
2. 02Admins: check the Tenant Outbound External Recipients report under Reports > Mail flow in the Exchange admin center.
3. 03Look for compromised accounts if the volume was not expected.
4. 04Send newsletters and other high-volume external mail through a dedicated service such as Azure Communication Services Email.

Sources

What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.

• Email nondelivery reports and SMTP errors in Exchange Onlinelearn.microsoft.com
• Exchange Online limitslearn.microsoft.com