System is win2000 with sp4 & exchange 2000 with sp3. When i sent email to another email system(exchange 2003),I got a error message from Exchange system: xxx.com#5.5.0 smtp;505 Authentication required event id 4001: Message delivery to the remote domain 'xxx.com' failed. The error message is 'An SMTP protocol error occurred. The SMTP verb which caused the error is 'MAIL'. The response from the remote server is '505 Authentication required pls help,Tks a lot!
