Update 11/13/2023: We added new information on how to know when this change is released to your organization.
Today, we are announcing an update to our requirements for SMTP relay through Exchange ...
Updated Feb 22, 2024
Version 19.0
Blog Post
Carolyn_Liu
Microsoft
Microsoft"
In a hybrid environment, if an application sends an email to onprem exchange server and if those emails are sent to O365 EOP, does the above condition still applies to.
Meaning if the emails are sent from onpremise exchange servers with different p1 and p2 sender domains, will EOP still reject those emails based on the above change? Please clarify
"
Answer: Whether the sending server in your on-premises server is Exchange or not, does not matter. What matters is for those emails send by application, whether P1 domain is your accepted domain or not. Of course, if Exchange servers is configured to use cert, and the cert domain is the accepted domain (means you satisfy 1.a), then you are fine.