Sending Mail with PHP

Hi I try to send mail (like http://www.php.net/mail) and it works fine. I define my own headers. But my question is about "wrong mail delivery". I use exim4.34. When I send mail via PHP script, then I see in my logs: 2004-10-26 11:04:36 1CMNFs-00046O-T9 <= www-data@Host_domain U=www-data P=local S=913 And mail was deliver to specify (To:) header Mail arrive with correct From: header line. But problem is present when domain does not exist: (1) 2004-10-26 10:21:35 1CMMaF-0003Qm-IH <= www-data@Host_domain U=www-data P=local S=934 (2) 2004-10-26 10:21:35 1CMMaF-0003Qm-IH ** mail@nonexist.tld: Unrouteable address (3) 2004-10-26 10:21:35 1CMMaF-0003Qp-Jc <= <> R=1CMMaF-0003Qm-IH U=exim4 P=local S=1692 (4) 2004-10-26 10:21:35 1CMMaF-0003Qp-Jc => /dev/null <www-data@Host_domain> R=system_aliases T=**bypassed** So.. If domain was not exist (like (2)), then exim4 generate error message and send to....www-data@... (like (4)). Is some way to change it? I never set in any config these address. I try to set in mail header Return-Patch:, but it seems to no work :( I use debian version php: 4.3.9 -- I greet Wieslaw