What was the reasoning for using Spamassassin in preference to DSPAM ( http://dspam.nuclearelephant.com/ ) which seems a much cleaner solution to me.

Is there any possibility in the future that Zimbra will more more modular so that users can pick and choose between components such as an anti-spam product of their choice?

Those questions come with the warning that I'm a new linux user and I was just about to try DSPAM/Postfix when Zimbra came along.