6/25/2025 Important update regarding the cloud hosted Mailbox External Recipient Rate Limit: In order to reduce the impact on customers, Microsoft has again decided to delay the rollout of the cloud ...
Updated Jun 25, 2025
Version 14.0
Blog Post
We have a lot of external email that is sent as part of the business. All users are hosted in ExO, we are in hybrid with a few shared and DDLs on prem with Exchange 2019 also acting as an SMTP relay for over 2000 apps.
I have a scenario right now where one of our users needs to notify 30k external recipients (companies) about a financial change via a single notification email. If they send an email to a ONPREM DL with mail contacts as members (external) and onprem sends the emails back out via the hybrid servers to ExO to deliver, do those count again the ERR?
Same question but with on prem app's relaying via exchange 2019 SMTP onprem to external users, does that count?
thanks!
Tom