Fix double-encoding attachment headers in single-part rfc2047

* lisp/mail/rfc2047.el (rfc2047-header-encoding-alist): Don't
double-encode Content-Disposition in mails with no other body
(bug#56906).

diff --git a/lisp/mail/rfc2047.el b/lisp/mail/rfc2047.el
index bb0d646346cf9eab14892564888f663872fb27de..67874d508b1f0fb153cca652912b0f06252f51a0 100644 (file)
--- a/lisp/mail/rfc2047.el
+++ b/lisp/mail/rfc2047.el
@@ -45,6 +45,9 @@
   '(("Newsgroups" . nil)
     ("Followup-To" . nil)
     ("Message-ID" . nil)
+    ;; This header must be pre-encoded by the MTA, so avoid
+    ;; double-encoding it.
+    ("Content-Disposition" . default)
     ("\\(Resent-\\)?\\(From\\|Cc\\|To\\|Bcc\\|\\(In-\\)?Reply-To\\|Sender\
 \\|Mail-Followup-To\\|Mail-Copies-To\\|Approved\\|Disposition-Notification-To\\)" . address-mime)
     (t . mime))