Keeping user passwords in mail-server migration
We're planning a mail server migration in the next days. We are moving our domain from Qmail to a Postfix+Sasl+POP3/IMAP setup. At the moment, i have the updated list of current mail users, but not their passwords, and i need them for an efficient transparent (for the user) migration.
Through qmailadmin console, I can create, delete and modify users, and reset their passwords, but i have no clue on how to fetch their cleartext passwords. I need to use that info in a getmail/fetchmail script to retrieve messages into the new server (before MX dns entry change, since we´re also changing MX location too).
Does anybody know how to accomplish this? How can i get those passwords in cleartext? Then, how should i create the fetchmail script?
Thanks in advance.