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Recommendations for Tenant External Recipient Rate Limit (TERRL)

  1. Exclaimer Knowledge Base
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Payal Arya
  • Updated

Scenario

Microsoft has introduced a new tenant-level outbound email limit, calculated based on the number of email licenses assigned to the tenant. If a tenant exceeds its daily outbound sending limit, any additional messages to external recipients will be blocked, and senders will receive Non-Delivery Receipts (NDRs).
For more information, see Introducing Exchange Online Tenant Outbound Email Limits.

 

Resolution

Exclaimer is aware of this Microsoft-designed behaviour. This only affects Exclaimer Server-Side signature users, where external emails may be counted twice. Given that Exclaimer's limits are set very high, this is unlikely to impact your sending capacity.

Follow one of the suggestions outlined below:

Use Exclaimer Client-Side signature
We recommend using Exclaimer's Client-Side signatures to avoid this issue entirely, as no messages are routed through Exclaimer and therefore are not double-counted. Microsoft is exploring alternative anti-spoofing measures that do not involve double-counting.
Limit emails sent through Exclaimer 

Limit the emails sent through Exclaimer to only those requiring signatures.

You can do this by configuring the Identify messages to send to Exclaimer Cloud transport rule to apply solely to members of the group who require signatures.
 

NOTE: You can also reduce the number of users routing to Exclaimer.