[stomachmonkey]

Outlook uses a .pst file to store mail.

It's one file that acts kind of like a database.

Other mail clients are flat file, each email represented by an individual file.

The nature of the pst makes recovery much more difficult.

Who / how is your email handled. Where / what is your email server?

Your best / easiest shot will likely be at the server level.

This is the same employee you were having trouble with not too long ago?

Not much help now but for future reference you can always set up an alias or blind forward for an employees mail so you get a copy of it, for inbound at least.