I am currently having an issue running phpmailer with smtp authenticaton. The website is running on an IIS (Windows 2003) web server with PHP 5. The mail server (SmarterMail 5) is running through a secondary server on the same network. I am able to execute the script along with my configuration settings, however my problem is specifically with the host variable. If I insert mail.mailServer.com, I get a "220" response from mail.webServer.com. If I insert the ip address of the mail server, I still get a "220" response from the web server. It appears that it's redirecting for some reason. I also tried to telnet into the mail server from the web servers desktop, and when I would run a HELO test, it reported back the ip address of the web server I was currently on. Now, if I ping mail.mailServer.com from the web server, it would report the correct ip address back (which would show that my DNS settings are correct). I don't know if this information helps at all, but these were some of my findings. I have verified that the configuration settings are working by testing a generic host like mail.test.com, which reported an "unable to connect" error as expected. If anyone could shed some light on this, I would greatly appreciate it. Thanks for your time!