mail () will send to everyone except my own domain

Hello all, Having a real problem. Have written a very simple php email script that I'm testing on our server. The script works fine if I set the 'to' field as any email address but our own - i.e. xyz@hotmail.com This works fine, however as soon as I set the script to email me at the domain to which the server resolves too it fails. I do not get a error message, it says that the mail has been sent. The server runs Apache 1.3 and Php 4.1.2 (I will update to 4.2.2 once I have resolved this). The error logs on the server give no indication of any problem. I cannot work this out at all - it simply will not email to the same address as the DNS resolves its own IP address too. Our mx records are held elsewhere. I'm at complete loss on this one - I've been checking php.ini, httpd.conf etc etc and cannot work out why this is happening. Php.ini is set too: sendmail_from me@localhost.com sendmail_path /usr/sbin/sendmail -t -i smtp localhost do I need to set the smtp to point to the server that holds the mx records? any help/advice much appreciated, thanks, Gareth --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.380 / Virus Database: 213 - Release Date: 24/07/2002