So here we go again with Evolution ... This time I managed to screw up my font preferences (I just don't care for Courier very much) and subsequently pretty much every HTML e-mail I received would crash Evolution. After a couple of days of putting up with this and forcibly re-installing rpm after rpm, I found the culprit.
Long story short, if you run into this problem take a look at
.gconf/GNOME/Documents/HTML_Editor/%conf.xml
Yup, that's where the font preferences are stored. I can't believe I didn't find it earlier ...