General help

I've tried to find the answer but couldn't! Appologies in advance if this has been answered already. When students try to signup they enter their information and the message that an email has been sent appears on their screens. The only problem is that the emails are sent back to my (the administrator's) email. Does anyone know how I can remedy this? any assistance would be appreciated. Eric
An example of the message I receive is as follows:
This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

test@hotmail.com
SMTP error from remote mailer after RCPT TO::
host mx3.hotmail.com [65.54.167.5]: 550 Requested action not taken:
mailbox unavailable

------ This is a copy of the message, including all the headers. ------

Return-path:
Received: from nobody by server11.yourhosting.us with local (Exim 4.24)
id 1BFj87-0002WI-JI
for test@hotmail.com; Mon, 19 Apr 2004 19:28:51 -0500
To: test@hotmail.com
Subject: =?euc-jp?Q?Eric_Hagley's_EFL_Classes:_=C5=D0=CF=BF=A4=CE=B3=CE=C4=EA?=
Received: from phpmailer ([202.223.187.38])
by www.eflclasses.org with HTTP (PHPMailer);
Mon, 19 Apr 2004 19:28:51 -0500
Date: Mon, 19 Apr 2004 19:28:51 -0500
From: Eric Hagley
Message-ID:
X-Priority: 3
X-Mailer: PHPMailer [version Moodle 2004032500]
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Content-Type: text/plain; charset="euc-jp"