13.1.6.3 x-face-e21 (for Emacs 21.x)

With Emacs 21.x, you can use `x-face-e21.el' (ftp://jpl.org/pub/elisp/) instead of `x-face-mule.el' to display X-Face. In this case, bitmap-mule is not required. Do as follows:

(autoload 'x-face-decode-message-header "x-face-e21")
(setq wl-highlight-x-face-function 'x-face-decode-message-header)