OK, enough fooling around -- I did a clean reinstall of Slackware64 14.0 then did testing of sendmail:

• I named the box pita.lan;
• Set up my account;
• Sent mail from root to me, worked fine;
• Installed all stable patches (except the kernel patches);
• Sent mail from root to me and vice versa, worked fine, no runs, no drips, no errors;
• Upgraded to ksh93-2012_08_01-x86_64-1, did sendmail in both directions, worked fine (had to check just to see).

Going to upgrade the kernel and see what's what with that (if anything).

OK, upgraded to Kernel-3.2.45 (this box has Intel graphics), ran the sendmail tests in both directions, works fine.

Maybe it was the pita.com that was causing the problem (although my three other Slackware 14.0 boxes that are identical to this one worked fine to being with) but, whatever, the blasted thing is working fine so I'm going to mark this one solved.

I'm also going to change all the others to sname.lan and see how that goes -- just sounds like a good idea. None of these guys have service from the outside world (HughesNet just don't want ya doin' that!) and I don't have a registered domain name and I'm hoping that changed from .com to .lan will eliminate whatever glitch there might be.

Unless somebody's got a better idea about how to configure my LAN...

Thanks to all for the help.

The only good advice I can give you on this is to try to create a new thread dedicated to that problem :).

BTW, I'm curious too.

Cheers

Garry.

You can use this article as input:

http://computechtips.com/295/slackware-linux-pc-router