Function: mm-safer-encoding
mm-safer-encoding is a byte-compiled function defined in
mm-encode.el.gz.
Signature
(mm-safer-encoding ENCODING &optional TYPE)
Documentation
Return an encoding similar to ENCODING but safer than it.
Source Code
;; Defined in /usr/src/emacs/lisp/gnus/mm-encode.el.gz
(defun mm-safer-encoding (encoding &optional type)
"Return an encoding similar to ENCODING but safer than it."
(cond
((eq encoding '7bit) '7bit) ;; 7bit is considered safe.
((memq encoding '(8bit quoted-printable))
;; According to RFC2046, 5.2.1, RFC822 Subtype, "quoted-printable" is not
;; a valid encoding for message/rfc822:
;; No encoding other than "7bit", "8bit", or "binary" is permitted for the
;; body of a "message/rfc822" entity.
(if (string= type "message/rfc822") '8bit 'quoted-printable))
;; The remaining encodings are binary and base64 (and perhaps some
;; non-standard ones), which are both turned into base64.
(t (if (string= type "message/rfc822") 'binary 'base64))))