I am looking for some kind of filter rule for an account which should be at server side and not at user.

I explain the matter:
I have a group of users working under same department, all have their individual accounts. In addition, there is one account with the department name. I forward all mails inbound to this account to the respective department head, he reads mail and forwards the same to the users to whom it is finally for. This creates unnecessary internal mail traffic and unnecessary storage too.

If I can create filter rule (or similar) for this department's id, based on certain criteria mail shall drop into respective user's mailbox only.

Guidance or other solutions in the matter are welcome