If you can receive emails but can not send emails this usually means the authenication required by the outgoing (SMTP) server is not configured. If you can't send or receive emails the chances are your IP address has been auto banned, please go to this article instead.
Please check the following before you contact us.
1. 'My outgoing (SMTP) server requires authentication’ is not checked. In Outlook it is in advanced settings.
2. You are not authenticating with the correct email account. You must authenticate with the same account you are sending from. i.e. bob@yourdomainname can NOT authenticate for sending email using jon@yourdomainname