I do something similar. I have two users set up under Yarn, one called Default and one called Alan. I have two mailboxes I use regularly, but the mailboxes do not match the users. Most of the other stuff goes straight into the default inbox.
Any mundungus mail goes into a special folder called scatologymail.
With Yarn, I can just glance at the subject line in the scatology folder. But human emailers usually change the mundugus whilst the robots do not, so it all usually goes into the proper place. I also have a unique address on my web site and different addresses for mailists. The negative filtering removes the known rubbish. I started using different names so I could try and identify the original source of my name and also so I could easily filter out any name if it became a nuisance.