A couple of days ago I had a power outage. Since then Kontact crashes continuously. I have submitted 2 bug reports - there are at least 2 things I can do that get it to crash reliably. The bug reports are: https://bugs.kde.org/show_bug.cgi?id=250332 and https://bugs.kde.org/show_bug.cgi?id=250412.

Quite often I am unable to mark new messages as read. Then it will crash and after re-starting I have a few minutes where I can mark new messages as read. If I restart and wait before attempting to mark as read then it goes back to not being able to mark as new. I am also sometimes unable to move a message from one folder to another.

I have tried re-creating indexes, but this hasn't helped.

I tried creating a new user and copying .kde4/share/apps/kmail/mail to the new user. All the mails are there as expected, but after POPing new emails, the behavior is the same.

It is virtually unusable. If I get say 10 new messages, I will probably suffer 3-5 crashes before I manage to read them all and move to my various folders.

Does anyone have any suggestions on how to fix this (aside from giving up on kontact and moving to Thunderbird which I am starting to consider)?

Clearly some corruption somewhere, so the problem is finding where. You were quite right to start by rebuilding the index files. Since that didn't work, the next thing I'd try is renaming (I never delete files why troubleshooting) kmailrc, which is usually in ~/.kde.share/config/. If that doesn't cure it, replace your current kmailrc and continue using rename (and replace if it doesn't cure it) throughout the whole list mentioned in http://userbase.kde.org/KMail/FAQs_Hint ... me_machine - remember that for efficient troubleshooting you should only work on a single file at once. Good luck.

Renaming kmailrc did the trick.

Luckily I was able to import my long list of filters without a hitch. But I have had to redefine all my POP accounts and kmail settings, templates etc. A bit of a pain.

Wouldn't it be better if kmail had a kmailrc folder which contained a file for each type of setting?

Anyway, thanks for your help.