How to use the PHP mail() function?
To use PHP mail() function, you need to create a mailbox in the Mail section in the user panel and add it as a sender address in the header "From".
$to = 'email@example.com';
$subject = 'the subject';
$message = 'hello';
$headers = 'From: firstname.lastname@example.org';
mail($to, $subject, $message, $headers);