Dear
[name of former employee] is no longer an employee of this corporation and is therefore no longer authorized to act， in any form whatsoever， on our behalf.
I am requesting that this information be relayed to all of your department heads.
[name of former employee] is no longer an employee of this corporation and is therefore no longer authorized to act， in any form whatsoever， on our behalf.
I am requesting that this information be relayed to all of your department heads.