:group 'gnus-article-hiding)
 
 (defcustom gnus-visible-headers
-  "From:\\|^Newsgroups:\\|^Subject:\\|^Date:\\|^Followup-To:\\|^Reply-To:\\|^Organization:\\|^Summary:\\|^Keywords:\\|^To:\\|^Cc:\\|^Posted-To:\\|^Mail-Copies-To:\\|^Apparently-To:\\|^Gnus-Warning:\\|^Resent-From:\\|X-Sent:"
+  "From:\\|^Newsgroups:\\|^Subject:\\|^Date:\\|^\\(Mail-\\)?Followup-To:\\|^\\(Mail-\\)?Reply-To:\\|^Organization:\\|^Summary:\\|^Keywords:\\|^To:\\|^Cc:\\|^Posted-To:\\|^Mail-Copies-To:\\|^Apparently-To:\\|^Gnus-Warning:\\|^Resent-From:\\|X-Sent:"
   "*All headers that do not match this regexp will be hidden.
 This variable can also be a list of regexp of headers to remain visible.
 If this variable is non-nil, `gnus-ignored-headers' will be ignored."
                ;; Decode MIME message.
                (when gnus-show-mime
                  (if (or (not gnus-strict-mime)
-                         (gnus-fetch-field "Mime-Version"))
+                         (gnus-fetch-field "MIME-Version"))
                      (funcall gnus-show-mime-method)
                    (funcall gnus-decode-encoded-word-method)))
                ;; Perform the article display hooks.