[Mimedefang] No free slaves and high CPU usage

[Chris Henderson]

One of my mail servers is showing heavy load for the last few weeks.
When it's under heavy load, sendmail stops working for a few seconds
and when the load goes down, sendmail comes back to normal
automatically. This happens 2-3 times every hour, 24 hours. This
server is the same as far back as I can remember and nothing has
changed anywhere. When the server is under heavy load I get this
message:

"mimedefang[6136]: [ID 669130 mail.warning] mfconnect: No free slaves:
Need 1, found 0"

Under /var/spool/MIMEDefang I can see around 26710 directories that
starts with  "mdefang-m<random_numbers_and_characters>" - most of
which are empty.

Is this something that is causing high CPU usage on my system? Can I
delete these directories?

I don't have much experience with mimedefang & friends. I want to
increase the MAX_SLAVES parameter but not sure where to configure it.

Any help would be much appreciated. Thanks.