Timo,
Can you still reproduce this crash? http://dovecot.org/bugreport.html lists some things about how to get a core dump.
I changed things to try to get a core and, of course, for nearly a 2 weeks got nothing at all. Figures. After you released 1.1.2 I went ahead and updated. A few days later I got a nice core waiting for me.
Unfortunately I made the mistake of not watching the ports build and didn't see that that it lacked -g, so the backtrace is only partially useful.
#0 0x080ba927 in message_parse_header_next () (gdb) bt #0 0x080ba927 in message_parse_header_next () #1 0x080b7f8a in imap_write_flags () #2 0x080b85c7 in imap_write_flags () #3 0x080c4dfd in i_stream_read_data () #4 0x080bd07d in message_get_body_size () #5 0x0806149a in imap_fetch_deinit () #6 0x080600c1 in imap_fetch () #7 0x0805a5ea in cmd_fetch () #8 0x0805e7ee in client_handle_unfinished_cmd () #9 0x0805e7a7 in client_handle_unfinished_cmd () #10 0x0805ea2d in client_handle_unfinished_cmd () #11 0x0805ebf1 in client_input () #12 0x080c7c30 in io_loop_handler_run () #13 0x080c71ed in io_loop_run () #14 0x08065b64 in main ()
In an attempt to stop wasting your time I have recompiled with -g and an now running that set of binaries. The next time this happens I should have useful backtrace for 1.1.2.
I doubt the message itself had anything to do with it. Just deleting dovecot.index.cache probably fixes the issue?
Anyway I just tried causing the "Broken MIME parts" error myself. I couldn't get Dovecot to crash (and the problem got fixed automatically).
I've not gone as far as doing that. All of the users on this system use mbox format, so if you think it would help I can just run a find | xargs to remove all of the dovecot.index.cache files. However, if I do this I may deny you the chance to see what keeps causing this. Would you prefer I leave it and try for another core? The crashes do not happen enough that users are screaming for my blood, yet :)
John