This is a fanlisting for the music streaming service Spotify. The site is listed as a part of TheFanlistings.org, under the Computer Miscellany and Internet > Programs category. New members are of course most welcome, so don't hesitate to join!
Quite simply, a fanlisting is a site that gathers a list of fans of a particular subject. It is not a mailing list. If you're concerned about your e-mail address being listed, simply state on the join form that you'd like it to be hidden.
For more, visit TheFanlistings.org.