'(("Gmane" . "http://mid.gmane.org/")
("MARC" . "http://marc.info/?i=")
("Mail Archive, The" . "http://mail-archive.com/search?l=mid&q=")
+ ("LKML" . "http://lkml.kernel.org/r/")
;; FIXME: can these services be searched by `Message-Id' ?
;; ("MarkMail" . "http://markmail.org/")
;; ("Nabble" . "http://nabble.com/")