Thank you for your help.
I had been doing test emails from yahoo and i looked at the error message real close and it was saying that there was no MX or A record for the domain.com. I went back and added that MX record and now it works.
I would have gotten back to you sooner but I installed amavis-new, clamav, and spamassassin which messed the server up to where it wouldn't send out mail.... I uninstalled one at a time to find the culprit and it was amavis-new.
Afer I uninstalled everything I reinstalled dovecot-postfix ( aptitude reinstall dovecot-postfix ) and squirrelmail then rebooted the server to get it back to where it was.
Any ideas about the amavis-new.
I used this to configure amavis-new http://postfixmail.com/blog/?p=340
My install was pretty simple I installed Ubuntu Server 9.04 with lamp, open-ssh, and mail. Then after the server install I did (aptitude install dovecot-postfix) and (aptitude install squirrelmail) and of course (aptitude install apache2) I'm just setting up a web site with email and wordpress.