Problem with mail send using php on site

[plastilin]

Help me where to dig. Installed ISPCP 1.0.2 under Debian Lenny. Install new domain - domain.local, raised site. The site have a form to send an email message through the web interface using php, the name of the recipient address from the site is the same domain as the site itself (recipient@domain.local). Postage ISPCP function is not used, because there is already configured email server. The problem is that not leave messages on the user names if their domain coincides with the domain hosted on hosting. In other domains, which are not on hosting - everything goes without problems. In the log Postfix:

Code:

Jan 18 18:18:29 hostingsrv postfix/virtual[31728]: 140A294A30: to=<recipient@domain.local>, relay=virtual, delay=0.22, delays=0.07/0.12/0/0.04, dsn=5.1.1, status=bounced (unknown user: "recipient@domain.com")

How i can win this situation? Sorry For my english.