According to reports from other people, the SpamAssassin documentation
does mention using `cdcc info` to see if the DCC client is working,
but doesn't say why it matters or what you're supposed to look for.

It would be swell if someone with access to SpamAssassin mailing lists
or something could encourage that documentation to say that `cdcc info`
should find at least one preferablly more than half a dozen of the
public DCC servers.  If it doesn't, a likely cause is an interfering
firewall.  A common firewall configuration passes outgoing DCC/UDP/IP
requests to distant port 6277 but rejects responses.  That combined
with the DCC client code's retransmission mechanisms can multiply the
outgoing requests by more than 50 times.  (Never mind that large
multiplication applies only to dccproc and that recent versions of
dccproc should throttle the flood to a dozen or two every few minutes.)

(The above text has been provided by the DCC maintainer, Vernon Schryver
vjs<AT>rhyolite.com)