E-mail autoreply not "replying"

I don’t know if any of you have any knowledge of e-mail autoreply systems. I have set up an e-mail account on my friends web account and one of the facilities offered by the web host is an auto reply service.

If you mail the account directly from another email account the email is received and the system autoreplies fine.

I have a PHP contact form on the website that sends an e-mail to the account and the e-mail is received, but the autoreply does not work.

The web host says that it is something wrong in the PHP coding that is causing the problem, but they can’t say what and I don’t know enough about PHP to trace what might be causing it.

In your experience have any of you guys ever come across this issue at all and could suggest a means of rooting out the cause? Any ideas at all would be gratefully received.

The line of code that adds the recipient is:

The processing is done through a file called fgcontactform.php acquired from the DOWNLOAD button HERE

The rest of the php form after the page write up is validation similar to the contactform.php in the download.

I don’t know what I’m looking for that might cause this issue so any help is gratefully received.