Sending mail from PHP mail() all emails bounce back

Hello all,

In my website script i'm using PHP mail() to send emails but i'm hosting my email server outside virtualmin (domain registar free email service)

Whenever i use my website contact form and try to send an email "You have successfully submitted your Contact US!" but non of the emails get to my inbox (free mail account at domain registarr)

i really don't know what is going on and how to get it fixed. any help would be great

My php.ini ; For Unix only. You may supply arguments as well (default: "sendmail -t -i"). ; http://php.net/sendmail-path sendmail_path = /usr/sbin/sendmail -t sendmail_from = me@example.com

Thank you