Note - this is the formal situation on the hosting -
http://www.fasthosts.co.uk/knowledge-base/?article_id=65
PHP
Use the PHP mail function and set the mail from using the following line of code - replacing $email_from with the correct domain name.
* ini_set("sendmail_from", " $email_from ");
You need to add a fifth "-f" parameter to the sendmail function. This will set the name of the from address.
* mail($email_to, $email_subject, $email_message, $headers, ’-f’.$email_from);
This is covered in the article EXAMPLE: ’Form to Mail’ script using PHP.