I need help! Sometimes can send to xxx.net ,but sometimes can't send it. If the user can't send it ,user will get this messang "Delivery Status Notification (Failure),This is an automatically generated Delivery Status Notification. Delivery to the following recipients failed. 123@xxx.net " Final-Recipient: rfc822;123@xxx.net Action: failed Status: 5.5.0 Diagnostic-Code: smtp;530 authentication required for relay (#5.7.1) Why! How can I fix this problam? Is our server problam or xxx.net problam?

This seems to be a send connector problem. Look in your internet send connector properties if there is something strange. Ron

This also may relate to the xxx.net server problem where it is requesting for authentication from your relay server. You could also contact the other end administrator to allow your servers to send email to their relay server

The fact that you get this on one specific domain would tend to indicate the problem is not at your end. Your server is in the NDR message because their server is rejecting the message at the point of delivery. I wonder why you believe it is being rejected by Sender ID filtering? I would expect another message if that was the case. That message is often what you get when you try to send to a server that is designed to relay email out of a network, rather than relay it in. For example your server is connecting to another ISPs SMTP server they give to their customers to use. Please go through below troubelsooting : http://support.microsoft.com/default.aspx?scid=kb;en-us;821910 http://support.microsoft.com/kb/915863/en-us Dinesh S.

I am agree with Dinesh, WHat version of Exchange you have in your ENV ?. If exchange 2007 then i would suggest you to create one send connector for perticular xyz.com and test mail flow. Also check with send test mail thru SMTP command and test it. Numeric Code: 5.5.0 First Available: Exchange 2000 Service Pack 1 Possible Cause: Generic protocol error (SMTP error). The remote SMTP response to our EHLO with a 500 level error and the sending system will QUIT the connection and report this with NDR indicating the remote SMTP server cannot handle the protocol. (For example, if a Hotmail account is no longer active, a 550 SMTP error will occur.)Anil

Hi, Is the sender from internal user of your Exchange server? I knew the NDR was generated by your Exchange server. If the sender is the your exchange users not Internet user, the possibe cause is the destination server or the wrong receiving server is used. If the sender is not your exchange user, that is your Exchange server issue which could not relay the email by default. I suggest you enable SMTP log on the Send Connector and reproduce this issue, and collect the Protocol Log for the Send Connector, then post here for troubleshooting. AllenAllen Song