If you have problems with an exim + MailScanner config where emails get into your system but then they get stuck on queue and not delivered to final destination (incoming exim works but the one that sends email to the outside world after MailScanner does not) be sure to check the file /etc/exim/trusted-configs
Inside this file you must specify the two config files that MailScanner should use. For example:
/etc/exim/exim.conf
/etc/exim/exim_out.conf
Hope to save sometime to someone… 
