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 dorfdsl.de. Replace AT with @, like john+rsl AT example.org --> john+rsl@example.org. 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:
https://news.novabbs.org/computers/thread.php?group=news.software.readers Spammers can send their mail to isendrubbish@cartoonies.org Do NOT send mails there unless you want to be blacklisted.