[Evolution] SpamAssassin no longer working

[Erik Moeller <moeller scireview de>]

I'm running evolution 2.4.2.1 on Debian testing. SpamAssassin 3.1.0 is
installed. When I do "ps aux | grep spamd", I get:

root       863  0.0  0.5  27324  3460 ?        Ss   Feb19
0:10 /usr/sbin/spamd -c -m 10 -d --pidfile=/var/run/spamd.pid
root       895  0.0  0.4  27324  3176 ?        S    Feb19   0:00 spamd
child
root       896  0.0  0.4  27324  3176 ?        S    Feb19   0:00 spamd
child

spamc and sa-learn also seem to be working fine from the command-line.

I have also enabled the evolution option "Checking Incoming Mail for
Junk". Spam filtering used to work, but as of a recent apt-get upgrade,
no spam is filtered anymore. I still can flag individual mails as junk,
but they only get deleted -- I don't see a "Learning junk" message
anymore, and it happens immediately instead of taking a few seconds as
it used to.

Any hints where I need to poke my system to make it work again?

Erik