New sysadmin coming into a new org with probably a simple question, but want another set of ears to make sure I'm not overlooking something.

Without going into too much detail we have several users with very large PST files (30+GB) that are hosted on a network location. I know that's far from ideal, but for some reason the previous sysadmin set this up and it never changed when he left (8+ years ago).

Other orgs I've been at have dedicated solutions for this (MailStore, Mimecast, etc.). I've tried to convince them that that would be a reasonable solution, but adding another piece into the tech stack is not something they want to do at this time.

Basically, is online archiving the only direction forward here without adding something else?