More details in message trace (client type and message class)
On on-prem exchange servers, there are valuable information that are showing what client was used to send a message or meeting (like AirSync or MOMT, etc.), and Message Class (like IPM.Note or IPM.Schedule.Meeting.Request, etc.).
This has proven to be valuable in determining some mailflow issues and would also be valuable information in Office 365 message trace.
I totally agree with this, I developed an interface and tool that parses OnPrem logs and output all the following information:
-Type of email (message, meeting request / decline / accept)
-Who is expanded from which DL
-Recipients status (TO, CC, BCC)
-If someone received because of a redirection or inbox rule, it is showing it
-If an inbox rule moved the email to a folder, it is showing it
All this is critical IT information for our IT support to users. It help us understand fast what happened to an email.
Tomorrow if we go to office 365, all this data is lost. We barely have "is delivered or not".