As it is adequately put here: http://bugs.kde.org/show_bug.cgi?id=151147 , IMAP filters in kmail in 3.5.8 is broken. However it was working fine in 3.5.7. Right now there is no 3.5.7 in the portage tree anymore and 3.5.9 is marked as testing. This means that kmail users who don't want to upgrade to testing are stuck with a broken kmail. I'm using separate ebuilds and did ACCEPT_KEYWORDS="~x86" emerge kmail to install testing versions of kmail and it's dependencies, and mostly it works fine. The problem is, this is an ugly solution and testing version of kontact that got pulled with this does not recognize the 3.5.8 versions of other kontact parts (knode etc), so kontact only has kmail now. So, I'm advocating making kde 3.5.9 stable because of this, unless other kde packages have deadly bugs that 3.5.8 does not have. Reproducible: Always
3.5.9 will be stabilised soon.
3.5.10 is stable, reopening to close