Automatically move attachments upon receipt

Gentleones,

I am using OSXS 10.3 (right now) with intentions of moving to 10.4 (eventually–it’s a $’s thing) for a very, very small network. One of the things I’d like to do with my Server box is to take any E-mail with attachments to one particular address and shove the attachments into a directory, rename the attachment according to the subject, and delete the source message. The directory for these attachments must be perm’d in such a way that Apache can see them (www:www, for example).

I’m using Postfix, clamav, SpamAssassin and amavisd, of course.

The questions here to be answered are:

Which is the best place to do this processing? Postfix? Amavisd?

What can I do to minimize the effort required to redo this installation when I do decide to upgrade to Tiger Server?

Thanks,
Bill