We have mail archiving. It is done on a separate server (product called GFI MailArchiver). All incoming and outgoing email is archived. What would be recommended retention periods? Would it be a good idea to have differing retention periods based on job function? In other words, would the “general populace” have a different retention than tellers? A suggested for C level (CEO, CFO, etc.) such as never.

Suggestions that have been made:
Tellers 1-3 years
General populace 7 years
C level – 7 years or permanent.

Exchange mailbox has been based on size or mailbox and not date. We are looking to implement having 365 days. Is that sufficient or too short, too long?