Can only be done if you specifically backed the server up with a product that allows 'brick level' backups. Such as Arcserve or Veritas, these products will allow you to backup a mailbox from the server, you can then restore just that mailbox or a message contained in that mailbox - if thi swas used then check with the vendor documentation to see how to properly restore just a message.
If you have not used these products or are using the NT backup utility. Than your only option is to restorethe data to a server which is a non-production system. Do not restore over your current system otherwise you will lose more than a couple of messages.
For future mishaps, you may wish to implement deleted item retention, by default this is not enabled. From Exchange admin, open the properties to the Pirvate Information store on the server, you can set the number of days for Deleted Item Retention. Typically set this for 7 - 14 days (note: using this will increase the size of the private store). It will give your users the ability to recover deleted items with-in this window.
Probably clear as mud. But hope it helps.
Good luck.
Rick_Platt@hotmail.com