We have a hybrid exchange system with exchange 2013 on-prem and and O365 account for our Skype For Business. At present, our O365 is sending mail down to our exchange serves based on IP address and Microsoft wants to change that. Microsoft wants to go to cert based connectivity. So, the connector reads O365 can receive email from any device that has "this certificate.mydomain.com. Of course, Microsoft is telling us to get a wildcard cert and put it on any device wanting to send mail to the O365 connector and that's fine.
However, before I make the change, my boss is asking me for a report that shows all devices connecting to the O365 connector and the certificate they are presenting, if any. I think he wants to see all of the FROM addresses to make sure we don't have a random device sending mail from something other than a *.mydomain.com email address.
Can someone help me with a power shell that will show me all connections made to the O365 connector and the FROM address the sender is using so I can confirm that all outbound connections to the O365 connector are falling within the *.mydomain.com cert that we will be using?