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>I can understand your point that a connector is not needed in my scenario per Microsoft, but shouldn’t there be some concern about the outcome? Messages meant for one tenant were redirected to another based on a connector and shared Microsoft infrastructure? What would happen in a scenario where two different tenants both had connectors for the same set of IPs or certificates and they were on shared Microsoft infrastructure as in the scenario we experienced?
Answer: to clarify, this only impacts mails sent from your organization, it won;t affect other people's mail. Basically you created the Inbound connector, and requested this: any mails are sent from my domain(regardless of the recipients), and using this certificate blah, should be attributed to me.
Again, Inbound OnPremises connector should NOT be used for mails coming common 3rd party cloud services, in fact no connector is needed in this scenario.
We are planning to add restrictions in the future for such behavior. However, there may be other cons associated with it.