(last updated 2012-09-23)

Resource Identifier (RI) Scheme name: message 
Status: provisional

Scheme syntax:
   message:<MESSAGE-ID> or message://<MESSAGE-ID>

Scheme semantics:
   Direct link to specific email message

Encoding considerations:
   Unknown, use with care.

Applications/protocols that use this scheme name:
   Supported by Mail since OS X 10.5

Interoperability considerations:
   Unknown, use with care.
   May be unsuitable for open use on the public internet.
Security considerations:
   Unknown, use with care.
Contact:
   Registering party: Dave Thaler <dthaler&microsoft.com>
   Scheme creator: Apple
Author/Change controller:
   Either the registering party or someone who is verified to represent
   the scheme creator.  See previous answer.
References:
  http://daringfireball.net/2007/12/message_urls_leopard_mail

(file created 2012-09-23)