I own a VPS where kloxo is configured with qmail. I am able to send and receive emails online. I can receive emails locally but am unable to send it. Following is the outlook error message
The message could not be sent because one of the recipients was rejected by the server. The rejected e-mail address was [email protected]'. Subject 'aoa', Account: 'mail.ebookszilla.com', Server: 'mail.ebookszilla.com', Protocol: SMTP, Server Response: '553 sorry, that domain isn't in my list of allowed rcpthosts (#5.5.3 - chkuser)', Port: 25, Secure(SSL): No, Server Error: 553, Error Number: 0x800CCC79
The reason for the error "553 sorry, that domain isn't in my list of allowed rcpthosts (#5.5.3 - chkuser)" is that your mail application has not authenticated to our mail server.
Basically, if you check your mail first for incoming messages, the server will remember your address for some time, and you will be able to send through it during that period without giving your username and password. This is probably the method you are using at the moment. The error message would appear after you have not checked your mail for some time, and you try to send. In this case, you should either configure your mail program to authenticate to the server in order to send, or check your email before sending.