is there a way of determining which 365 server the mailbox is on

It used to be on help, since blue upgrade this does not work.

I have tried the Remote Connectivity Analyzer (RCA) but it idid not want to work for the account I entered, I am sure this was correct, as I can use it to log into office 365.

Is there anyway we can look at a message to determine which server it came from ?

JD