Nobody-Mail-Problem with PHP & CGI-Scripts

[JapAniManga.ch]

Hello,

I have 3 WHM/CPanel Servers and they have all have the same Problem: Mails are rejected from some Providers (Example: Swissonline.ch and GMX.de) with following Message:
#*#*#*#*#*#*
This message was created automatically by mail delivery software (Exim).

A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed:

xxxxx@swissonline.ch
SMTP error from remote mailer after MAIL FROM:&nobody@servername.domain.com& SIZE=1673:
host relay01.cablecom.net [62.2.33.101]: 550 5.0.0 &nobody@servername.domain.com&... Invalid Address
#*#*#*#*#*#*
Normal Mail via WebMail or Mailprogramm does work but when the Mail are send via CGI- or PHP-Script (vBulletin) then some Providers block them with the Error-Message

I mean this can't be a Problem that I only have it. Have this Problem on 3 Servers (1 x RH7.2 + 2 x RH7.3) who are Setup from 3 different Providers so this can't be a Setup-Problem. Other People on others Servers (Plesk, with a CP, etc.) who also use vBulletin does also not have this Problem so that also can't be a Script-Problem ! ..................

Does anybody know how this Problem can be solved ? CPanel-Team ???

[MOD: Did not know if I should write this in the CPanel- or WHM-Section, so when here false please move it]

[feanor]

Marco-

does this hostname actually resolve to the outside world:

servername.domain.com

(whatever it actually is, does it resolve on the internet as a whole?
Is reverse dns setup for the base IP of the machine in question?

[JapAniManga.ch]

@feanor: You was right it is 'Reverse DNS', I just found at WHT a Link (http://www.dnsstuff.com/) and the Test shows that I have no 'Reverse DNS'.

Question: Is there a WHM-Script how I can work in RDNS ?

[JapAniManga.ch]

@feanor: RDNS is now activaded and the Hostname does resolved but I have still the Problem

[JapAniManga.ch]

Will now make a Ticket to CPanel Team.