Version:           1.5.1 (using KDE 3.1.1)
Compiler:          gcc version 2.95.3 20010315 (SuSE)
OS:          Linux (i686) release 2.4.18-4GB

After my last bug (http://bugs.kde.org/show_bug.cgi?id=41514) was said to be from slow sorting and efforts seem to have focused on that, I have opened a new bug. I have installed SpamAssassin to filter out the huge masses of spam I receive. I am using the spamd/spamc combination, where I run spamd in the background and pipe messages in a filter through spamc. This can be a slow process however, especially since I am using the VipulsRazor rule in SpamAssassin as well. As a consequence, it can take several minutes to get my mail. That's not a problem.
The problem lies in the fact that KMail is completely unusable during that time! I can not read messages allready received, I can not create a new messages, I can not even continue work on a message I was allready working on when (automatic) mailchecking begins! Now _that_ is irritating. Why should filtering messages block the entire UI? I would like to propose two changes to tackle the problem, but if you see another way: just as well:
1) first download the messages to a local queue, and then filter from that queue. This way, the connection with the ISP is not kept open longer than needed as it is now.
2) move messagereceiving and/or filtering to a separate thread, so the app can keep functioning. I really don't think that timers are a solution here, since you are working with external programs you'll have to wait for.