email archival to reduce mailbox size

[Geoff Nordli]

I have a client using the Bynari Outlook connector, which uses local
ost files to store data.

OST/PST files have performance issues with larger files (greater than 5GB).

I am not looking for something that archives all emails at the smtp
connector level, but something that is more at the mailbox level, and
maybe based on the mailbox size or date.

Deleting the email isn't an option since they need to keep it.

Any suggestions on how I can reduce the size of the mailbox.

I am looking for an open source solution.

Maybe I just write a script that moves email from the "live" server to
an "archive" server.  They can access the archive server via imap,
instead of the bynari connector.

thanks,

Geoff