Have a glimpse at this site and check if your SMTP relay server is configured properly... http://support.microsoft.com/kb/230235 Regards, Mahadevan MCSE: Messaging IT Infrastructure Engineer ________________________________ From: exchangelist-bounce@xxxxxxxxxxxxx [mailto:exchangelist-bounce@xxxxxxxxxxxxx] On Behalf Of Navin Balakrishnaraja Sent: Wednesday, October 25, 2006 7:46 AM To: exchangelist@xxxxxxxxxxxxx; exchangelist@xxxxxxxxxxxxx Subject: [ExchangeList] 550 relaying mail to domain.com is not allowed Hi , I am getting this error 550 relaying mail to domain.com is not allowed I get this error randomly to different domains and it vanishes and comes back suddenly. Any ideas??? Thanks navin Confidentiality Statement: This message is intended only for the individual or entity to which it is addressed. It may contain privileged, confidential information which is exempt from disclosure under applicable laws. If you are not the intended recipient, please note that you are strictly prohibited from disseminating or distributing this information (other than to the intended recipient) or copying this information. If you have received this communication in error, please notify us immediately by return email.