One rule that may be good, depending on how much of the mailing list email you receive is promotional, is to match "A header called List-Unsubscribe exists" and move that to Promotional. Then you could put any exceptions that it categorizes wrong above it.
That's a good idea. Although, oddly, some of the emails that have an Unsubscribe button have no List-Unsubscribe header.
How would you suggest to solve the following problem: let's say I have archived all my mail (inbox zero); how do I now see the emails that are important to me (i.e., everything that was not labeled e.g. with promotions)?
