Excerpts from mail: (31-Mar-98) Not relaying spam? by Vikas Agnihotri
How can I prevent my host/machine being used as a stepping stone to relay
spam? Any machine can just connect to my SMTP port 25 and relay spam off
of it, right?
I am running sendmail 8.8.8
But to answer your question, check out
<http://www.sendmail.org/> has some other links for fighting spam with
sendmail which may be of interest to you.
Follow-ups on this topic should be probably posted to the comp.mail.sendmail