I have a customer who needs to keep an AD User account active but remove all ability to have emails sent to this User, without deleting the mailbox or the User account, with the ability to undo what we did quickly.
Basically, a staff is on leave for an undetermined amount of time. In the meantime, I need to block all external access for the staff (easy to do by changing passwords and disabling remote acess) but also need to make sure any emails sent to the User are returned as invalid to the sender so they know to contact someone else, just as if they were terminated. We cannot delete the account or mailbox.
I have Disabled the User account but emails still route to the Inbox and the Out of Office reply is sent to the Sender. We do not want this as the Senders are not paying attention to the reply. I have considered removing the email address from the User's AD account but am not sure if this will put the mailbox in a disconnected state, at which time I will need to monitor and make sure Exchange does not delete it following retention policies, since it is disconnected. I am in the process of backing up the mailbox to a PST in case anything is lost but I am sure another method is available - I just don't know what that method is.
Please advise on options native to Exchange and/ or AD to allow this, if possible.