Hi, I am running Exchange 5.5 sp4 on Winnt 4.0 sp6a. I have recently got a client who runs Exchange 2000. Sometimes the client is not able to send mails to our server. Their server sends them the NDR saying: our message has been delayed and is still awaiting delivery to the following recipient(s): abc@xxxxxxxxxxxx Message delayed I/O error encountered during command: (message data) Status: 4.4.2 (Persistent transient failure - routing/network: bad connection) I am wondering whether there is something to be done at my end. Regards, Chand