The PHP mail() function is not working from my cpanel.
My cpanel ports are all open and by default the email ID is also set in cpanel.
MY code
$to = "rahul@gmail.com";
$subject = "My subject";
$txt = "Hello world!";
$headers = "From: webmaster@host4future.in" ;
mail($to,$subject,$txt,$headers);
Your code seems correct, but most hosts block the mail function by default and/or prevent the user nobody from sending emails.
In Tweak Settings on WHM, try turning off the option "Prevent 'nobody' from sending mail".
In the PHP Configuration Editor (in advanced mode) check if the mail function is listed in the disable_functions directive.
If none of that work, check if the Exim is up and running and if the sendmail_path in php.ini is correct.