This is a web gateway to the Usenet, a worldwide distributed network.
That instace allows posting via your web browser, to get an account send an email to mm+rsl AT Replace AT with @, like john+rsl AT --> This is to make harvesting much harder for spammers. Regardless of which server you use, all messages will be distributed to all usenet servers.

A beginner's guide is available here: Getting Started with Usenet
If you have any problem setting it up, you can ask via the web here: Spammers can send their mail to Do NOT send mails there unless you want to be blacklisted.