I finally have DSPAM integrated in my mail setup (running Postfix running DSPAM via mailbox_command which then hands off to procmail). The problem I'm not having is that the users DSPAM sees are of the form "user@domain" instead of just 'user'. Where that is showing up the most is with the DSPAM web-app and the auto-spam trainer accounts. Those accounts end up being "user@domain@domain" and it is just getting ugly :)
I think Postfix is what is ultimately handing the full username off to DSPAM? But I'm not sure what to do to chop off the domain component? I use system accounts so the short accounts is really what should be used. I'm actually surprised procmail seems happy with the setup, but everything is working with the full names apart from what I mentioned above.