Hi, I have a recently installed Exchange 2007 server which is rejecting inbound mails from certain senders. 99% of all mails are coming in with no problems but those senders with problems are getting the NDR :- Remote host said: 550 5.7.1 Requested action not taken: message refused There is no spam filtering software on this server as all inbound mails are filtered via MessageLabs. MessageLabs have confirmed that they are NOT blocking these mails and can see them listed in their outbound mail logs. I'm at a loss with this problem and fairly new to Exchange 2007. Any help from anyone would be very much appreciated. Thanks Chris

You'll want to enable smtp (protocol)logging on the receive connector. this will let you see what is actually going on. http://technet.microsoft.com/en-us/library/bb629472(EXCHG.80).aspx

Thanks Mike, I will give this ago and see what the logs reveal!

ok, please keep us posted with whatever you find and mark as answered if that helps.

Hi, Before going on, I would like to confirm the whole topology of your Exchange server. Was Edge server deployed? Whether Anti-spam agent component was installed there? Did you configure any Junk-email on the client side? As Mike said, enable the log on receive connector in order to check whether the email was rejected by Exchange server or MessageLabs. Additionally, if the sender receives NDR, we can ask for header of the NDR by right clicking on NDR message in Outlook and select"Message Options" If the message is coming through MessageLabs, we need to check with MessageLabs, if message tracking on recipients domain server, that indicates the cause is on Exchange server side. Thanks Allen