Hi, Can I confirm with someone if this is correct. I found a user showing up in the properties of another user under "last logged on by". What I did was asked userA of the mailbox if he given delegated rights to userB and confirm that userB has "reviewer" rights to userA calendar. Will this display the "last logged on by" of userB saying userB accessed userA mailbox regardless if userB has only reviewer access. Thanks.

Yes... reviewer means they can read part of the mailbox so they are logging on. Even more tricky, a free/busy check (which by default, anyone in the org can do) will show as a logon. So it doesn't point to any suspicious behavior. There are more detailed auditing methods available (depending on your version of Exchange) if you are trying to watch for people doing things they shouldn't be doing.

Yea..I just need that as a confirmation. Thanks cn9