I've had some fun with this... Rather than the "simple appliance" that we really wanted, we've ended up with all the joys and pains of Linux/Postfix/Amavisd/Spamassassin - but adding MySQL/Apache/Maia, and PHPMyAdmin and Webmin. Fun. Had some real fun when I flooded the system by: (a) turning off connection-stage blacklisting and, (b) cranking amavisd logging. Massive backlog of queued mail... then crashed due to filling the disk! Panicy attempt to mount in some more disk space before I found the d**n amavids log lurking in some dumb place. Well, I learnt a few things :-)
occasional jottings on what I'm up to...