Quaylan

I have set up the server correctly to best i can tell. it is Pop3 service with smtp on IIS 6.0 on server 2003 small business ed. I am useing authentication useing windows built in user groups. Here is my SMTP Virtual Server properties: Authentication: all are check (anonymous acess,Basic,integrated Windows Authentication) If i uncheck Anonymous I no longer can log into the server to send emails, With it checked i still require a password and username..... dont understand this. under connection i have checked all except the list below, and under relay I have check only the list below, then i have checkes Allow all computers which successfully authenticate to relay, regardless of list above. Then I have all my users added to my security list. other then that all settings are default to the quick wizard. The problem i am haveing is : I can send and recieve email from inside the domain , and i can recive email from out side the domain. I cannot send email to some people out side of the domain. Example I can send email to runbox.com and yahoo.com hot mail ect. But not to any other email sites. I get a error message: The message could not be sent because one of the recipients was rejected by the server. The rejected e-mail address was 'somesite@somewhere.com'. Subject 'can't tell yah', Account: 'mail.mydomain.com', Server: 'mail.mydomain.com', Protocol: SMTP, Server Response: '550 5.7.1 Unable to relay for somesite@somewhere.com', Port: 25, Secure(SSL): No, Server Error: 550, Error Number: 0x800CCC79 can any body help?