PHP newsletter mail sending problem

Hi,

Why can not send emails Gmail, Yahoo, Hotmail, etc through PHP newsletter. Mail seems to send (no error message and PHPlist reports it was sent successfully) but recipients never get it and it doesn't show up in statistics. But it works fine when i sent a mail to the same domain (like email@mydomain.com) where i installed the PHPlist.

If you type a gmail/yahoo email in the subscription, then you will not get any mails even confirmation mail.

I have tried many PHP newsletter scripts but i can not sent emails to Gmail, Yahoo, Hotmail, etc. It works only with the same domain (like email@mydomain.com)

Is there anything to do with settings from the control panel.

Thx,

Wallace