Hacking, hacking and hacking.
The last weeks I spent my time with debugging, configuring, screaming and jumps of joy with Postfix.
The good news: Virtual domains working with postfix, courier-imap, mysql, amavisd-new, spamasassin, TLS/SASL is working.
The bad news: I can’t get sasl working with mysql, still working on that one.

More for my own reference:
<br /> Jan 19 18:12:30 mail postfix/smtpd[81211]: OTP unavailable because can't read/write key database /etc/opiekeys: No such file or directory<br />
fix: add the follwing line to /usr/local/lib/sasl2/smtpd.conf:

sasl_auxprop_plugin: mysql login plain crammd6 digestmd5

OTP is btw: One Time Passwords. (for mail?!)

Multiple accounts in with SSL to your imap.
Only one at a time is able to connect. is quite stupid. It opens up at least 3 connections at a time to your imapd.
Courier has a default of 4 connections / ip.
Hack your /usr/local/etc/courier-imap/imapd and change connections/ip to a reasonable ballpark figure (I entered 50).

Convert mbox to Maildir?
Forget it. Do it by hand, the tools don’t work.

The most usefull howto’s I could find: Seems dead :(