Hello We have two Windows Server 2003 AD sites liked by VPN tunnel. When users from site A forwards Outlook invite that was sent by an external user to a user in site B he gets the following NDR Your message did not reach some or all of the intended recipients. Subject: FW: xxxxxxxxxxxxxxxxxxxxxxxxxxx Sent: 3/16/2010 1:35 PM The following recipient(s) cannot be reached: Karen xxxxxxx on 3/16/2010 1:35 PM The e-mail account does not exist at the organization this message was sent to. Check the e-mail address, or contact the recipient directly to find out the correct address. <mail.xxxxxxx.org #5.1.1> When the same invite is forwarded to user in the same site A, no NDR is generated And when an invite that was created by user in site A is forwarded to users in site B, no NDR is generated either So it only occurs When users from site A forward Outlook invite that was sent by an external user to a user in site B The user Karen XXXXX has been deleted from AD 4 years ago Strange issue, any advice? Thank you

Hi, Please check whether the below article can help you:http://support.microsoft.com/kb/312433 Thanks Allen

Allen, it's been a while but I just got to the point when I was able to recreate the AD account and Exchange mailbox and still getting this NDR - this is so strange.