Strange locally-originating spam messages from sport.qc.ca

[Julian Gilbey <julian@d-and-j.net>]

I'm getting a significant number of spam messages being sent to my MTA
(exim) for the address FRPJXbKeKuek at sport.qc.ca, and now I'm
starting to see some sent to www-data at aether.toine.be.  What is
disturbing is that the machine is on a local network, and my
internet-facing router does not forward anything to this machine.  So
I presume that these mails are originating from the machine itself.

I have another machine on the same network that is internet-facing and
also receives similar messages.

I don't know how to track down the source of these mails, and I wonder
if somehow my machine has picked up some sort of virus.

I wonder if anyone has any idea about how to track this down?

Thanks!

   Julian