Comment 14 for bug 560144

Shake, the difference between Karmic (1.82-2ubuntu1) and Lucid are really minor (attaching).
You can see them yourself, via:
1. bzr branch lp:ubuntu/postfix-policyd
2. cd postfix-policyd
3. bzr diff -r tag:1.82-2ubuntu1..tag:1.82-2ubuntu5

I suspect this is related to (changes in) dbconfig, which gets used for setting up the MySQL user.

Apart from that, it may be system specific (new install, upgrade, ...).

To debug this further, you may want to look into dbconfig, I cannot help you with that unfortunately.
Also, trying to install the Debian package (.deb) on the Ubuntu system, where the Ubuntu package is failing might give some hint(s).