I am looking to migrate users from an OS X server using the default cyrus mail store. I've read that imapsync is the way to go, but I don't have the passwords for all 700+ accounts. Frankly, I'm surprised that this method is so popular as it is not common practice to track user passwords.

Only option I can think of is to reset everyone's password and do the migration then. I suppose if this were a regular unix server I might simply make a backup of the shadow file, reset all passwords, do the migration, and then put the passwords back, but this is OS X with a password server. Can I backup and restore the password server? How can I make a mass password change like that?