I have never seen crashes on filter (automatic or manual). The problem noticed on manual filtering of many mails (a whole folder of several 100 Mo's) is that the computer gets very busy, so it takes a big while to filter, but then it works.
Using 6.10. -- applying filter on kontact and it crahes https://launchpad.net/bugs/90701 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs