well I have read up on this and to my understanding relaying is the process or having a sendmail server forward mail that did not originate from that server, out of that server...well I thought I had it. so I setup 2 centos boxes. I put them both on the example.com domain. the sendmail server is on station17.example.com which is also called mail.example.com in my dns (set up with a mx record). my client which is running evolution is on server1.example.com. now...I started dovecot and sendmail on station17 and made sure to enable protocols pop so I could receive mail. I opened up sendmail.mc and made only 2 changes...I commented out (dnl) the 127/localhost line which to my understanding meant sendmail could receive mail from outside the local machine...then I went to the line that says LOCAL_DOMAIN(`localhost.localdomain') and did a yy/p so that the line was copied below. then changed localhost.localdomain to "example.com". I then left the mail directory and ran make -C /etc/mail, and then service sendmail restart.

I then setup a user called casper on the sendmail box (station17). I sent a message to that user using the mail command and it showed up in the /var/spool/mail/casper file. --- here is where I am confused. I went to my other machine "server1.example.com" and setup evolution. well I was able to receive the message via pop that I had sent to casper...but when I tried to send a message to casper it says
RCPT TO <casper@mail.example.com> failed: <casper@mail.example.com>... Relaying denied

hmm...I am trying to send to a user on that very machine...and I opened commented out the 127 line in sendmail and put the domain both machines are on (example.com) in the LOCAL_DOMAIN part of the sendmail file...so why should it say I am trying to relay? I am sending to a local client on the sendmail server and since I got a pop message from that client I assume sendmail knows casper is on its own server. so what gives...am I totally not understanding what relaying is or what I need to get this working? I know there is a access file in the /etc/mail directory in which you can put domains allowed to use the server to relay...but I am not trying to relay just to send to a local user named casper I setup...

thanks much I am sure I am missing something simple.

btw I put the domain both machines are on...example.com in the access file and now it works...so I guess everything I have read about what relaying is is wrong?