Sorry to say that the good news about this issue were only partial. The email page is indeed sending emails, but in my inbox I only get the sender's email address and the Subject Title, no text.
I talked to the iXWebhost guys and after they spent some time trying to solve this issue, they told me there's a problem with the page's script. They sent me a "test_form.php" containing the code they used to send me a test email, which I got well, including the text.
Attached you will find the test_form in question.
Any suggestions will be highly appreciated.