Question : Your message did not reach some or all of the intended recipients

Hi,
We are currently running Server 2003 SBS, Exchange 2003 along with Outlook 2003 on all our client machines. One of our staff members is trying to email to a particular address that they were able to reach late last year but now bounces back with the following error:

Your message did not reach some or all of the intended recipients.

      Subject:      Test Email
      Sent:      1/02/2007 2:23 PM

The following recipient(s) could not be reached:

      ***@***.***.edu on 1/02/2007 2:23 PM
            You do not have permission to send to this recipient.  For assistance, contact your system administrator.
            <'Our Server'.'Our Domain'.'Our Bussiness'.com.au #5.7.1 smtp;554 5.7.1 <***@***.***.edu>: Recipient address rejected: Unable to verify mail server HELO identification from DNS entries>

So far i have conducted a blacklist scan, searched the quarentine area of our Trend email filter and tried to send the email my self with admin rights. I haven't had any luck with either so i was hoping some one here could help us out.

Thank you in advance.

Answer : Your message did not reach some or all of the intended recipients

Is there any way you can contact who you are trying to email? Theres a chance that it could be an issue there end with here HELO mail server and not yours.