dsync to backup to directory?

Hello,

We have a hosting operation and are interested in offloading mail for some of our machines to a separate machine.

We want the ability, though, to migrate accounts between the “offloaded” and “unified” configurations.

Toward that end, is it possible to “merge” two different mail directories (either maildir or mdbox) via doveadm? “doveadm backup” looks like the closest match, but it doesn’t appear to accept an arbitrary directory as its synchronization source.

Thank you!

-Felipe Gasper Mississauga, Ontario