sylpheed crashed everytime i opened the preferences dialog. Removing the lines "enable_pspell", "pspell_path" and "pspell_sugmode" from ~/.sylpheed/sylpheedrc fixed this problem. I think this was caused by the switch from pspell to aspell.
ah yeah, that would explain it. if, in fact, you'd recompiled sylpheed-claws after the pspell->aspell switch, things should've been ok...
I did compile sylpheed. apspell was installed as dependancy of sylpheed-claws-0.8.2 while emerge -u world.