Short answer is, you can't. Read on for more info.
We at Servosity completely redesigned our SaaS backup from the ground up because we were so disappointed with our first attempt. It was buggy, slow, unreliable, constantly errored out, and was always a toss-up whether a restore would actually work.As we began building, we asked ourselves what was the "One Thing" our software had to do. The answer we finally boiled it down to was "It has to restore anything from any time, no chance that our partners want something that we don't have"
So as part of this design philosophy, in service of that "One Thing" we made some choices. We provided unlimited retention, so if it's ever been backed up, we've got it. We'd backup everything we could possibly get our hands on (Exchange, OneDrive, Teams, Sharepoint, etc.) and just bill per mailbox to keep it simple. Finally, the only way we could guarantee that no mailbox was every missed, was to ensure that every mailbox from the creation of the account until it's removed from our portal, would be automatically added to the backup source and backed up for as long as it existed.
We understand that this is not the ideal solution for every partner, and that's ok. We learned a long time ago that building everything for everyone means that you end up with complex product, with loads of ways to misconfigured and miss things, and we decided we're not going to be that company. We want to make backup software that just works the way it should.
We're always happy to hear your feedback and discuss any of our policies if you'd like to email feedback@servosity.com.