Your PHP mail() script emails always show "From: cPanel-username@servername".
You can change that by adding the following code:
Then just add $headers to the mail function. See the related article for a complete script.
You can also add CC and BCC to your emails by adding this code:
IMPORTANT - You must add the header variable as the 4th attribute in the mail() function. EXAMPLE - mail($to, $subject, $message, $headers);