Comment 1 for bug 689411

I could work around this problem by adding a '--chuid Debian-exim' parameter to the start-stop-daemon call in /etc/init.d/mailscanner -

start-stop-daemon --start --quiet --nicelevel $run_nice --chuid Debian-exim --exec $DAEMON --name $NAME -- $DAEMON_ARGS \
    || return 2

I could also find more people having the same problem:

http://ubuntuforums.org/showthread.php?t=1313599
http://www.howtoforge.com/the-perfect-spamsnake-ubuntu-jaunty-jackalope
http://www.bluequartz.us/phpBB2/viewtopic.php?t=108939

The problem seems to be, that the mailscanner version used in karmic and lucid is not compatible with Perl 5.10