Spitfire Mail: public keys and avatars

GET /avatar/<hash>
  Avatar of a @spitfiremail.com address (Libravatar).
  hash        md5 or sha256 of the lowercased address
  s           size in pixels, 1-512 (larger gives 512); omitted: a square of the picture up to 512, rounded up to 16 24 32 48 64 80 96 128 160 192 256 384 512
  d           without an avatar: 404, mp, identicon, retro, robohash
  f=y         always the default image
  original=y  the uploaded picture, not resized
  domain      sender's domain: answers for addresses on other domains too,
              from that domain's Libravatar server (_avatars-sec._tcp)

  /avatar/$(echo -n alice@spitfiremail.com | md5sum)?s=128

GET /avatar/sub/<id>
  Avatar of any Weforge account by its Zitadel user id, 404 without one.
  s, original=y  as above

  /avatar/sub/123456789012345678?s=128

GET /.well-known/openpgpkey/spitfiremail.com/hu/<zbase32 of sha1 of name>?l=<name>
  OpenPGP public key (Web Key Directory).

  gpg --locate-keys alice@spitfiremail.com