We are experiencing a very weird email problem. When any user on our exchange server whose exchange display name (that name you see when you list the global address list) starts with "g" (upper or lower), tries to send an email to anyone on the domain @163.com (located in China) the following error message is returned to us: ===============RETURNED MESSAGE==================================== -----Original Message----- From: System Administrator Sent: Tuesday, 3 September 2002 3:08 PM To: Qi Zeng [China] Subject: Undeliverable: test Your message did not reach some or all of the intended recipients. Subject: test Sent: 3/09/2002 3:08 PM The following recipient(s) could not be reached: Qi Zeng [China] on 3/09/2002 3:08 PM Unable to deliver the message due to a communications failure The MTS-ID of the original message is: c=US;a= ;p=COM10 Pty Ltd;l=SARAH-020903050733Z-408 MSEXCH:IMS:COM10 Pty Ltd:COM10_DOMAIN:SARAH 3550 (000B09AA) 550 System is busy. =====================RETURNED MESSAGE=================================== Does anyone have any idea as to why this is happening. I could understand if all our messages were being returned, but only those whose display name starts with a g??? I've searched on the web for the error message "550 System is busy" but I've found very little. I've done an integrity check across the directory and private information store databases but no errors were revealed. PLEASE HELP!!!!