const emlParser = (encoded) => {
  let
  decEml   = '' ,
  keyInHex = encoded.substr (0, 2) ,
  key      = parseInt (keyInHex, 16)
  for (let n = 2;
           n < encoded.length;
           n += 2
  ) {
      let
      charInHex = encoded.substr (n, 2) ,
      char      = parseInt (charInHex, 16) ,
      output    = char ^ key
      decEml += String.fromCharCode (output)
    }
    return decEml
}
function emlDecoder() {
  const
  eml =
  document.getElementsByClassName("eml")
  for (let i = 0; i < eml.length; i++) {
    let
    elEml = eml[i] ,
    encoded = elEml.dataset.encoded,
    decoded = emlParser(encoded)
    elEml.textContent = decoded
    elEml.href = 'mailto:' + decoded
  }
} emlDecoder()