Hello
I'm planning to migrate a multi server installation of ZCS NE 6.0.15 to either a multi server ZCA (appliance) or multi-server ZCS ("proper") 8.x installation. Once we do this (which would be in a few months, or so), we'd like to migrate ALL of our domains and users more or less at once. We're doing tests now.
Thing is - we've got like 13'000 accounts and about 2'000 domains and a mail store of about 2TB.
Would ZxMig actually scale for such a medium sized installation?
One problem I foresee is the duration of the whole process. To not risk losing any mails, I guess I should stop delivery and also make IMAP/POP3/Webmail/… inaccessible to users (→ downtime). But that just cannot take days, as you might guess 
I'm a bit unsure - is it worthwhile to invest time and effort into ZxMig, or is that just too big for this tool?
Thanks,
Alexander