The server will prompt for a password only if the box 'Always request authentication...' is checked in Tools/Account Settings, Server Settings for the news account. Some servers don't require authentication. If you select the news account in the left pane of Account Settings, there is a drop-down menu to select the Outgoing Server (SMTP), which can be one of the servers for your ''mail'' accounts. But it's usually not necessary to use an smtp server, since most posts to a newsgroup are made to the news server as new posts or follow-ups. The dialog in your picture wouldn't work anyway as you've entered a news server instead of an smtp, i.e. mail, server.