Bad HELO – Host impersonating domain name

Hello,
I’ve 2 DA servers:
web.server.com – web server, MTA is stopped, local mail transfer is off in DirectAdmin.
mta.server.com – mail server (smtp/pop3/imap) – DNS (named) service IS disabled.

Domain test.example.com is added on both servers. And now all works fine, but when I send e-mail using SMTP (mta server) from PHP script (on web), I got en error im exim (on mta):

H=rev.web.server.com (test.example.com) [IP_OF_web.server.com] rejected EHLO or HELO test.example.com: Bad HELO – Host impersonating domain name [test.example.com]

The solution is to add this to config of phpmailer:
$mail->Hostname = "web.server.com";
$mail->Helo = $mail->Hostname;

The problem is that a domain test.example.com exist on both servers. PHP mailer by default use a _SERVER["SERVER_NAME"] as HELO.

How to fix a problem gloabally?
Releated: http://stackoverflow.com/questions/3…n-from-cli-cro
http://forum.directadmin.com/showthread.php?t=54272

Thank you.