We are still calculating and doing tests so we don't have final scaling numbers yet. We would love to learn some numbers from your side though. Besides trying the beta out (we always like that
) we also are interested in average mailbox size, what your bandwidth from the backup server to O365 is etc... (And if you don't want to share these numbers public, you can always PM me
Feel free to try it out with a couple of 100 mailboxes, that would be no issue. Maybe the initial download of mailboxes can take quite some time so ideally you start this on a Friday or so...