Everyone pay attention. This is the error that I get when sendmail attempts to send mail on a BRAND NEW XServe. This was the result of PHP's mail() function, but the UNIX mail command does the same thing.
May 22 13:58:41 servername sendmail: h4MHwfRo009460: email@example.com, ctladdr=admin (501/20), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=30037, relay=localhost [127.0.0.1], dsn=4.0.0, stat=Deferred: Connection refused by localhost
Every other dicussion group references this article as a solution, but IT DOESN'T WORK. I've tried it many times now.
My solution is to install Postfix (www.postfix.org). I just posted this as an FYI to anyone who is running around posting this article in discussion groups.
Once again: this article + mac os x server = sendmail is still broken.
If anyone has actually fixed this problem on their server, post and let us know.