I feel like the mailing list is sort of a poor-man's notification system in this case... several bug tracking systems I've worked with (commercial and free) come with a healthy notification system for custom-tailoring one's notifications using various attributes - it seems this is a feature still lacking in Trac.
There are rss feeds for about any query you can do in trac, so that should allow you to filter in (or out) most of the things you want.
-- Adrien Destugues / PulkoMandy http://pulkomandy.ath.cx