Hi, We are currently using Exchange Server 2000 with Service pack 2, we are using a single exchange server for 3 domains, we are able to send messages internally, the problem is when i send messages to external network (Internet), iam not able to send, i tried using Outlook Express and Microsoft Outlook, i have configured the SMTP Virtual Server for External DNS queries to ISP Server IP Address, and tcp ip configuration DNS Address to ISP Address, but iam getting the error like : "The message could not be sent because one of the recipients was rejected by the server. The rejected e-mail address was 'sekar@xxxxxxxxxxxxxx'. Subject 'VJT-22', Account: '168.192.20.37 (1)', Server: '168.192.20.37', Protocol: SMTP, Server Response: '550 5.7.1 Unable to relay for sekar@xxxxxxxxxxxxxx', Port: 25, Secure(SSL): No, Server Error: 550, Error Number: 0x800CCC79" Please help me resloving the problem, thanks in advance. D.D.Ramnarayanan ____________________________________________________________ Get advanced SPAM filtering on Webmail or POP Mail ... Get Lycos Mail! http://login.mail.lycos.com/r/referral?aid=27005