[Exim] "neither action flags nor mail addresses given"?

Hi!

The setup on my server (running Debian GNU/Linux unstable and Exim
3.36) is as follows:

                 via spamc
   fetchmail ------------------> exim

In /etc/fetchmailrc I have the following line:

   mda "/usr/bin/spamc -u sbellon | /usr/sbin/exim -oMr spam-scanned \
                                                   -i -f %F %T";

(In fact, it's not split across lines but it's in one line in my config
file and it's present for all local users, four in total.)

Most of the time, everything works fine as expected. But some evil SPAM
messages trigger this error message by Exim:

"neither action flags nor mail addresses given"

Then, this particular mail is not fetched, but stays in the mailbox.
This leads to the problem that after some time, my mailbox is full with
such SPAM articles. And even worse, in some conditions (I haven't yet
found out which ones) even articles that would fetch ok otherwise
aren't fetched anymore until I manually delete the offending mail from
the mail server manually.

So, what is this "neither action flags nor mail addresses given"
problem and how do I fix it?

If you need my exim.conf, just give me a shout. I didn't want to post
16 KB here if not necessary.

TIA.

--
Stefan Bellon * <mailto:sbellon@sbellon.de> * <http://www.sbellon.de/>
PGP 2 and OpenPGP keys available from my home page

'Work fascinates me - I could sit and watch it for hours'