Comment 1 for bug 268479

I have the same problem.
I think you also have a gmail account, because I noticed that the gmail plug-in is cause of this crashes.
The temporary solution is to check mails from gmail via pop plug-in.

To do it you have to delete your old configuration (I did it by this: "find ~ -name mail-notification -exec rm -r {} \;" and deleting this passwd form seahorse, the second action is optional) and add your new account via pop.

I hope some developers repair this, because checking gmail via pop sucks.

Cheers