Index: gnus-art.el
===================================================================
RCS file: /usr/local/cvsroot/gnus/lisp/gnus-art.el,v
retrieving revision 6.248
diff -u -r6.248 gnus-art.el
--- gnus-art.el	2002/09/27 08:09:05	6.248
+++ gnus-art.el	2002/10/16 18:14:10
@@ -5325,19 +5325,23 @@
 
 (defcustom gnus-button-prefer-mid-or-mail 'guess
   "What to do when the button on a string as \"foo123@bar.com\" is pushed.
-Strings like this can be either a message ID or a mail address.  If the
-variable is set to the symbol `ask', query the user what do do.  If it is the
-symbol `guess', Gnus will do a guess and query the user what do do if it is
-ambiguous. If it is one of the sybols `mid' or `mail', Gnus will always assume
-that the string is a message ID or a mail address, respectivly.  See the
-variable `gnus-button-guessed-mid-regexp' for details concerning the
-guessing."
+Strings like this can be either a message ID or a mail address.  If
+the variable is set to the symbol `ask', query the user what do do.
+If it is the symbol `guess', Gnus will do a guess and query the user
+what do do if it is ambiguous.  See the variable
+`gnus-button-guessed-mid-regexp' for details concerning the guessing.
+If it is one of the sybols `mid' or `mail', Gnus will always assume
+that the string is a message ID or a mail address, respectivly.  If it
+is a function, Gnus will call this function with the string in
+question as the only argument.  The function should return non-nil
+value, if the argument is supposed to be a message ID."
   ;; FIXME: doc-string could/should be improved.
   :group 'gnus-article-buttons
   :type '(choice (const ask)
 		 (const guess)
 		 (const mid)
-		 (const mail)))
+		 (const mail)
+		 (function :tag "Iff function evaluates to non-nil")))
 
 (defcustom gnus-button-guessed-mid-regexp
   (concat
@@ -5361,6 +5365,10 @@
     ;; otherwise 'ask the user.
     (if (eq pref 'guess)
 	(if (string-match gnus-button-guessed-mid-regexp mid-or-mail)
+	    (setq pref 'mid)
+	  (setq pref 'ask)))
+    (if (functionp pref)
+	(if (funcall pref mid-or-mail)
 	    (setq pref 'mid)
 	  (setq pref 'ask)))
     (if (eq pref 'ask)