Updated April 21, 2025: We have updated the timelines below. Thank you for your patience.

To reduce the risk of misuse and abuse of Exchange Online resources and ensure service availability for all users, we’ll soon introduce new tenant-level outbound email limits, known as the Tenant External Recipient Rate Limit or TERRL. The TERRL restricts the number of external recipients a tenant can send email to per day. If the limit is exceeded further messages sent to external recipients from the tenant will be blocked until the volume for the last 24 hours drops below the quota. A tenant’s TERRL quota is calculated based on the number of email licenses a tenant has purchased. Here is the formula used to calculate a tenant’s quota:

500 * (Purchased Email Licenses^0.7) + 9500

To help admins plan and track their outbound email volume, you’ll find a new report in the Exchange admin center: EAC > Reports > Mail flow > Tenant Outbound External Recipients Rate. This report shows the current volume of external recipients, your tenant’s daily quota, how much of the quota is used, and the number of recipients that were blocked if the limit was exceeded. The report will also show if enforcement for the limit is enabled or disabled. For example, for tenants who have more than 500 email licenses it will show “Disabled” until May 1st, the day we’ll start to enable enforcement for tenants who have more than 500 licenses.