Version:           1.8 (using KDE KDE 3.4.1)
Installed from:    Mandriva RPMs
OS:                Linux

There is a long (and seemingly growing) list of options of kmail filter actions but none of them allow one to pass messages to /dev/null.

Simply passing to trash is not a replacement for /dev/null.  It still requires time and effort by the user to go to the trash folder and empty it.  There are messages (spam) that I simply do not want to waste time dealing with at all.  They take up harddrive space and time as I have to manually delete them.  I use bogofilter as a spam filter.  It works close enough to 100% that I now trust it enough to simply have any and all messages it deems to be spam be made to "go away".  I don't want to waste time fiddling with the spam, that's bogofilter's job.  I would just like the option of passing any messages labeled "SPAM" to /dev/null.  I never need know they ever existed and they never need take up residence on my harddrive for even a short period of time.
   I waste lots of time every day dealing with spam.  It goes to a spam folder.  I was keeping it in an archive for future training of bogofilter but I have accumulated enough now that it is no longer useful nor desireable to keep any more.  It is also not desireable in any way, shape, or form to manually deal with it.  I do not generally close kmail down.  It runs continuously with my computer so the "empty trash on exit" option is virtually useless and manually selecting "empty trash" is no better than manually selecting the messages and deleting them without the trash middleman.  Some messages are simply a waste of time to deal with.  Having an ability to pass to /dev/null removes the waste and eliminates the time wasted dealing with it.  
   Please add a filter action that would allow one to pass messages matching a filter rule to /dev/null.  Really, the trash folder is not the same.