There is nothing special about configuring and running mail software under Linux (any more). Accordingly, you almost certainly do NOT want to be posting generic mail-related questions to the comp.os.linux.* newsgroups.
Don't post in comp.os.linux hierarchy unless it's really linux specific, for example : "Which options was Debian 1.2 sendmail compiled with ?" or "RedHat 5.0 smail crashes when I run it".
Let me repeat that.
There is virtually no reason to post anything mail-related in the comp.os.linux hierarchy any more. There are existing newsgroups in the comp.mail.* hierarchy to handle *ALL* your questions.
IF YOU POST TO COMP.OS.LINUX.* FOR NON-LINUX-SPECIFIC QUESTIONS, YOU ARE LOOKING IN THE WRONG PLACE FOR HELP. THE MAIL EXPERTS HANG OUT IN THE PLACES INDICATED ABOVE AND GENERALLY DO NOT RUN LINUX.
POSTING TO THE LINUX HIERARCHY FOR NON-LINUX-SPECIFIC QUESTIONS WASTES YOUR TIME AND EVERYONE ELSE'S AND IT FREQUENTLY DELAYS YOUR GETTING THE ANSWER TO YOUR QUESTION.
GOOD PLACES are :
comp.mail.elm the ELM mail system. comp.mail.mh The Rand Message Handling system. comp.mail.mime Multipurpose Internet Mail Extensions. comp.mail.misc General discussions about computer mail. comp.mail.multi-media Multimedia Mail. comp.mail.mush The Mail User's Shell (MUSH). comp.mail.sendmail the BSD sendmail agent. comp.mail.smail the smail mail agent. comp.mail.uucp Mail in the uucp environment.
There are many sendmail, smail and qmail mailing lists.
You can find addresses in /usr/doc/the_one_you_have_chosen.
There is plenty of excellent material provided in the other Linux HOWTO documents and from the Linux DOC project.
In particular, you might want to take a look at the following:
The following is a non-inclusive set of books that will help:
Managing UUCP and USENET" from O'Reilly and Associates is in my opinion the best book out there for figuring out the programs and protocols involved in being a USENET site.
Unix Communications" from The Waite Group contains a nice description of all the pieces (and more) and how they fit together.
Sendmail" from O'Reilly and Associates looks to be the definitive reference on sendmail-v8 and sendmail+IDA. It's a "must have" for anybody hoping to make sense out of sendmail without bleeding in the process.
The Internet Complete Reference" from Osborne is a fine reference book that explains the various services available on Internet and is a great source for information on news, mail and various other Internet resources.
The Linux Networking Administrators' Guide" from Olaf Kirch of the Linux Documentation Project is available on the net and is also published by (at least) O'Reilly and SSC. It makes a fine one-stop shop to learn about everything you ever imagined you'd need to know about Unix networking.