Updates to Tenant External Recipient Rate Limit (TERRL) Quotas for New, Trial, and Education Tenants

Tenant External Recipient Rate Limit (TERRL) quotas in Exchange Online will change starting mid-September 2026 for new, trial, and EDU tenants, adjusting limits based on tenant age and license type. Trial tenant quotas reduce to 500 recipients daily; EDU quotas use a new formula. Exceeding limits blocks outbound messages. What and Why: To strengthen protection against abuse and ensure fair use of Exchange Online resources, we are updating how the Tenant External Recipient Rate Limit (TERRL) quota is calculated for certain tenants. These changes improve how quotas account for tenant age (how long the tenant has existed since creation), trial subscriptions, and educational organizations using free Education (EDU) licenses. Rollout Schedule: General Availability (Worldwide): Rolling out beginning mid-September 2026 Impact on Your Organization: Who is affected: Newly created tenants (first 60 days) Trial tenants Educational organizations with free EDU licenses Platforms/Services: Exchange Online Exchange admin center (EAC) What will happen: TERRL quota calculations will change based on tenant status and licensing. New tenant quotas (based on tenant age): Less than 31 days: 10% of standard calculated quota 31–60 days: 25% of standard calculated quota More than 60 days: 100% of standard calculated quota Trial tenants: Daily TERRL quota reduced from 5,000 to 500 external recipients Tenants with free EDU licenses (e.g. A1 licenses): New formula applied: 500 × (Purchased Email Licenses^0.7 + Free EDU Licenses^0.3) + 9500 Free EDU licenses contribute to the quota at a lower weighting than purchased licenses Tenants without free EDU licenses: Existing formula remains unchanged: 500 × (Purchased Email Licenses^0.7) + 9500 If a tenant exceeds its quota: Additional outbound messages to external recipients will be blocked until usage falls below the rolling 24-hour limit Senders will receive one of the following Non-Delivery Reports (NDRs): Trial tenants: 550 5.7.232 — Message blocked due to trial tenant external recipient limit Non-trial tenants: 550 5.7.233 — Message blocked due to tenant external recipient limit Action Required / Recommendations: No immediate action is required. Recommended actions: Review the Tenant Outbound External Recipients Rate report in the Exchange admin center: EAC > Reports > Mail flow > Tenant Outbound External […]

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