This is a question that pops up occasionally. If you want to remove a user mailbox, but keep the user account active because he will still be connecting to the network how do you do it? Right-clicking the user mailbox in Exchange 2010 displays options like 'remove' and 'disable.' Clearly I don't want to disable the mailbox because that will just disable the user mailbox instead of removing it right? Wrong. Disable is actually what you want to click to remove the mailbox while keeping the user account in Active Directory. Yes, the mailbox will be disabled for a while and not removed, but after a period of time (depending on your Exchange setup) the mailbox will be removed (deleted) from storage.
Yes, it's strange but clicking disable will remove exchange properties from the user account then the disconnected mailbox will be setup for deletion. Doesn't it seem like 'remove' should do this?