Not another contacts and mailing problem?! - Joomla! Forum - community, help and support

i've spent best part of day trawling through forum , changing lots of combinations of settings on joomla based site no avail - have site have number of contacts , i'm having e-mail problems....

i seem have no problem validation e-mails being sent out when new users register - problem seems occur (so far) when try use contact form e-mail address not end in site's domain, mail doesn't make specified inbox.

i.e.
for site http://www.somedomain.com, e-mail through contact form deliver e-mail bill@somedomain.com not ben@anotherdomain.com

its new site there's still time other symptoms appear, has shown during testing , need sorted before go live.

here's details site:
joomla version: 1.0.12
server os: linux
web host: apache 1.3.37
path sendmail: /usr/sbin/sendmail
php version: 4.4.3

many of these details taken cpanel page site (an on-line control panel).  hosting company dataflame.

according dataflame faqs on e-mailing, smtp not require authentication.

i have contact entry set-up in joomla follows:
name: admin
e-mail: admin@somedomain.com

the admin@somedomain.com receiving e-mails , can mailed through contact form.


on joomla global configuration mail tab have following:
mailer: smtp server
mail from: admin@somedomain.com
from name: admin
sendmail path: /usr/sbin/sendmail
smtp auth: no
smtp user: admin@somedomain.com
smtp pass: {password specified smtp user account}
smtp host: localhost


so have tried?  every reasonable combination can think of using following:
changing mailer php & sendmail.
setting smtp auth yes.
editing components/com_contact/contact.php file adding following line @ beginning
    ini_set("sendmail_from", "admin@somedomain.com");
editing components/com_contact/contact.php file replacing
    mosmail( $email, $name , $contact[0]->email_to, $mosconfig_fromname .': '.$subject, $text );
        with
    mosmail( $mosconfig_mailfrom, $mosconfig_fromname, $contact[0]->email_to,$mosconfig_fromname .': '. $subject, $text );


everything fine if contacts going used contact site administrator.  unfortunately need keep directory of contacts on site (that special users adding to), , e-mail addresses work , personal ones.

so of in mind have insight might try next?

can reproduce bug on host? sounds misconfigured server.