We have around 15 users who all access Outlook via Remote Desktop on to a Server 2008 terminal server. Email is done by Exchange on SBS 2003. All users can send to one recipient except one. She gets the message below. The recipient exists at the domain, everyone else can send. This NDR is generated for this user only and happens whether we send via DNS direct from Exchange, or via the ISP's mail gateway. Does anyone know why this happens?
Your message did not reach some or all of the intended recipients.
Subject: test email
Sent: 09/05/2011 14:32
The following recipient(s) cannot be reached:
'User@recipients_domain.com' on 09/05/2011 14:32
The message could not be delivered because the recipient's
destination email system is unknown or invalid. Please check the address
and try again, or contact your system administrator to verify
connectivity to the email system of the recipient.