Please Help - Need to recover deleted emails fast

Please Help - Need to recover deleted emails fast

Hi All 

Ive had some trouble with a person who works for me that has deleted some important invocing emails which I need to recover as fast as possible. Ive gone into their account and they seem to have deleted evidence which I need to get back in order to better understand what has actually gone on between my employee and the client involved.

Please can someone advise if this is possible or not ?