(defvar mew-highlight-url-face 'bold nil)
(setq mew-bold-url-size nil)
(add-hook'mew-init-hook
 '(lambda ()
    (and window-system
         (define-key mew-message-mode-map [mouse-2] 'browse-url-at-mouse))
    (define-key mew-message-mode-map "\C-c\C-b" 'browse-url-at-point)))
(add-hook 'mew-message-hook 'mew-message-highlight-url)
(defun mew-message-highlight-url ()
  (let ((url-regex "\\b\\(s?https?\\|ftp\\|file\\|gopher\\|news\\|telnet\\|wais\
\|mailto\\):\\(//[-a-zA-Z0-9_.]+:[0-9]*\\)?[-a-zA-Z0-9_=?#$@~`%&*+|\\/.,]*[-a-zA
-Z0-9_=#$@~`%&*+|\\/]")
        overlay)
    (save-excursion
      (goto-char (point-min))
      (while (re-search-forward url-regex nil t)
        (setq overlay (make-overlay (match-beginning 0) (match-end 0)))
        (overlay-put overlay 'face mew-highlight-url-face)
        (overlay-put overlay 'mouse-face 'highlight)
        ))))