In this new blog post Kae Verens shares a method he came up with to change over about 300 domains' worth of email over from qmail to posfix in an orderly, automated fashion.
Yesterday we had to move about 300 domains from one machine to another. We bought a new machine recently and are taking this opportunity to move from Qmail (difficult to use, in my opinion) towards Postfix. After doing one or two by hand, i decided that's stupid - why not just automate the whole thing.
The script reads from vqadmin and pushes that information over to mailadmin who makes the emails over on the postfix side. The script makes heavy use of the cURL extension to get the job done.