UriSchemes/mailbox

"mailbox" is uriReg:schemeName of [
  dc:description """Mail folder access""";
  is uriReg:specifies of [
    = <http://developer.netscape.com/support/faqs/champions/client_tech.html>;
    dc:title """Netscape DevEdge Online FAQ - Client Technical""";
    dc:creator [
      dca:agentName "Netscape Communications Corporation"];
    dc:date "1999"; ];
]
.

• spec: Netscape DevEdge Online FAQ - Client Technical

This looks like a case of UriSpaceSquatting.----

See also other UriSchemes.

We're using NotationThree here, assuming TheUsualPrefixes.