Strange Error when using mail() PLEASE HELP



When trying to use mail() in my php script, I get the following error...

/etc/aliases: line 21: cannot alias non-local names: Error -30991 /dead.letter... Saved message in /dead.letter HTTP/1.1 200 OK Date: Sun, 09 Feb 2003 15:35:29 GMT Server: Apache/1.3.27 (Unix) PHP/4.2.3 X-Powered-By: PHP/4.2.3 Keep-Alive: timeout=15, max=100 Connection: Keep-Alive Transfer-Encoding: chunked Content-Type: text/html 2e0

Since that e-mail address DOES NOT appear anywhere in my script, I'm assuming that it's a linux or php config error, not a script error; however, my web site hosting company (that maintains the server) says that they don't troobleshoot 3rd party scripts.

Can someone please tell me if this is most likely a script error, or a configuration error on the server. Thank you for your time and attention.
Hi! actually this mail-adress not have i'm trying send some test messages and get Mail Delivery Subsystem message sorry that user not present :^(
By the way you may set youre mailserver for more short messages like user not present....