Mitigate TERRL Impact While Using Skyhigh Email DLP
Microsoft now enforces a daily limit on the number of outbound external emails a tenant can send through Exchange Online, called the Tenant External Recipient Rate Limit (TERRL). When a transport rule routes emails to the Skyhigh Email DLP solution, Microsoft currently counts each external email twice. When outbound emails reach their limit, you will receive Non-Delivery Reports (NDRs).
To maintain the continuous flow of the external outbound emails, perform the following steps:
- Check the outbound external email traffic limit in the Microsoft Exchange Admin Center (EAC) (EAC > Reports > Mail Flow > Tenant Outbound External Recipients Rate). The outbound external emails limit varies with the Microsoft Exchange Online license type.
- Review your traffic volume for the outbound external emails limit using the EAC report.
- If you are approaching or exceeding the outbound email limit, raise a Microsoft support ticket to request an exception. The exception allows your tenant to bypass the limit and maintain the continuous flow of emails without triggering NDRs.
For assistance with a Microsoft support ticket or other queries, contact Skyhigh Support.
To know the Microsoft announcements about TERRL, see Introducing Exchange Online Tenant Outbound Email Limits.