Rated 3 out of 5 stars
This later version now works for me on Thunderbird 3.0.1. While I was waiting for it to be fixed, I found ShrinkPic from http://www.onthegosoft.com/shrink_pic.htm?referer=shrinkpic
This addresses all the requests for features to be included in Auto Resize JPEG but of course it's not a Thunderbird add-on. Hopefully Auto Resize will incorporate some of these requests soon.