sorry for posting one on other :blush: but i had to add an important new info about my situation. i prepared a simple code to test if the problem is derived from the enhancement or from my hosting company requirements. i uploaded it to remote host and when i tried it out i got my test emails with success. So i guess problem is something about this enhancement :(
the code i tried is as below :
<?php
mail("sales@*******.com", "Email Test", "Line 1 TestingnLine 2 Another Line of Text nLine 3 Even more Testing");
echo "Okay";
?>