Update 9/17/2025: Updated GCC dates.
As with all cloud services, Exchange Online imposes service limits to prevent misuse of Exchange Online resources and ensure availability for all users. For exa...
Updated Sep 17, 2025
Version 20.0
Blog Post
till now I have engaged MS support 2 times and both time they weren't able to disclose details on the report data and even went on to tell me to "believe" they are correct. I am pretty confident there is some wrong data there .... and to show you what I am talking about I am gone show an example
I am migrating this customer to EXO, via hybrid , we are using "Centralized Mail Transport" on-premise
TotalMessages in24h - 2280 (sshot has cutshort data) : This is mainly due to messagetrace showing messages sent TO EXO hosted External Recipient from on-premise mailboxes...
ExternalMessages - 330 : removing received messages and messages sent to accepted domains ..
ExternalMessages from Mailboxes in EXO : 24
ObservedValue: 960
- The first problem here is, as usual, in the message trace I see (this is a problem into itself) messages sent from on-premise users (so mailbox yet to be migrated to exchange online) to external recipients who are themselves hosted in EXO . Are these Counted ??? these messages DO NOT effectively transit from "my tenant"
- If these messages are not counted (as it should be since they are not relayed thru EXO) these 2 users have sent 24 messages in 24 hours how do we get to 960 ?
- Even if these messages were being counted, I sit at a count of 330 messages sent to external domains ... how do we get to 960 ?
I feel the data you are providing, be it via commadlet\Report blatantly inadequate, how can you possibly think to impose a limit as potentially destructive as this without giving me the data on which your are basing the limit.
The time frame you are giving customers to adequate to these new limit is too short, I mean 2 months (1 month left now) is basically a joke ..
Arindam_Thokder
Microsoft
Microsoft1. can you elaborate "...messages sent from on-premises users to external recipients who are themselves hosted in EXO". Do you mean Other Exchange Online Tenant? Can you track these messages in your own tenant?
2. You are filtering emails based on message count, whereas we calculate this based on Recipient count.
1. Yes I can see messages sent from on-premise mailboxes to Other Exchange Online tenant Recipients (so external recipients) in my EXO Tenant Message trace , like this one this has been sent from an on-premise mailbox to an external recipent hosted on EXO as you can see I only see its landing on The receiving tenant ..
so my question is are these calculated on TERRL ?
2. Are not mail sent to multiple recipient decoupled in the message trace ? so if I send a message to 3 recipients will I not see 3 different message trace line ? if that is not the case how can I get the data needed cause The report provided in "Reports -> Mail flow -> Tenant Outbound External Recipients" does not give details ... so please provide me with a way to check this- Arindam_Thokder
If you see messages sent from on-premises mailboxes to Other Exchange Online Tenant Recipients (so external recipients) in your EXO Tenant Message trace, there is a configuration issue at your end, and it is called wrong message attribution. And yes, these messages are counted. To fix the issue, watch this video where I explained the issue in detail - (99) Establishing Exchange Hybrid Mailflow - YouTube (watch the full video for better understanding. Your scenario starts at 16:30 min)
Thank you for the clarification, so this answer my first question, and I thank you for that, I am indeed in this predicament, what about my second question, how do I get a detail of the message\recipients included in the observed value ?
Thanks