Andrew Stobart

This is a quick tip for something that I'm asked quite often. The scenario is that you have created an inbound connector in Exchange Online and want to verify that mail which should be coming in through that connector really is; as opposed to mail coming in through a different custom connector or even the default hidden inbound connector. The quickest way I’ve found to do this is through PowerShell. First, find a message that was received by Exchange Online.

Consider the following mail flow. On-premises environment --> Your Exchange Online tenant --> External Recipient With the above mail flow, you may find yourself in a situation where you need to validate that the outbound message was properly attributed to your Exchange Online tenant. I recently worked with an organization that controlled two Exchange Online tenants and found that their mail was not relaying out of the tenant they expected.