[resending, as my original post never made it to the group]

Gnus (latest CVS) generates wrong MIME encoded messages
when an inline PGP signature is included along with an attachment.

When a multipart message is sent, gnus builds a buffer by adding each
part sequentially, top to bottom. But there's a bug with the code that
generates inline signed parts: the point is not moved back to the bottom of
the buffer, and so the following parts are inserted at the wrong place.

A fix is simple: after each part is generated, move the point back to
the end.  i.e, in mml.el, around line 590, where it iterates over each
part, inserting a separator between each part and at the end.

             (let ((cont cont) part)
                (while (setq part (pop cont))
                  ;; Skip `multipart' and attributes.
                  (when (and (consp part) (consp (cdr part)))
                    (insert "\n--" mml-boundary "\n")
                    (mml-generate-mime-1 part))))
              (insert "\n--" mml-boundary "--\n")))))

Just insert "(goto-char (point-max))" after the call to mml-generate-mime-1:

              (let ((cont cont) part)
                (while (setq part (pop cont))
                  ;; Skip `multipart' and attributes.
                  (when (and (consp part) (consp (cdr part)))
                    (insert "\n--" mml-boundary "\n")
                    (mml-generate-mime-1 part)
                    (goto-char (point-max)))))
              (insert "\n--" mml-boundary "--\n")))))

I've tried it on various messages containing various attachments and it
seems to do the trick. A diff against mml.el 7.40 is attached.

Max.