+@item mm-body-charset-encoding-alist
+@vindex mm-body-charset-encoding-alist
+Mapping from @acronym{MIME} charset to encoding to use. This variable is
+usually used except, e.g., when other requirements force a specific
+encoding (digitally signed messages require 7bit encodings). The
+default is
+
+@lisp
+((iso-2022-jp . 7bit)
+ (iso-2022-jp-2 . 7bit)
+ (utf-16 . base64)
+ (utf-16be . base64)
+ (utf-16le . base64))
+@end lisp
+
+As an example, if you do not want to have ISO-8859-1 characters
+quoted-printable encoded, you may add @code{(iso-8859-1 . 8bit)} to
+this variable. You can override this setting on a per-message basis
+by using the @code{encoding} @acronym{MML} tag (@pxref{MML Definition}).
+
+@item mm-coding-system-priorities
+@vindex mm-coding-system-priorities
+Prioritize coding systems to use for outgoing messages. The default
+is @code{nil}, which means to use the defaults in Emacs, but is
+@code{(iso-8859-1 iso-2022-jp iso-2022-jp-2 shift_jis utf-8)} when
+running Emacs in the Japanese language environment. It is a list of
+coding system symbols (aliases of coding systems are also allowed, use
+@kbd{M-x describe-coding-system} to make sure you are specifying correct
+coding system names). For example, if you have configured Emacs
+to prefer UTF-8, but wish that outgoing messages should be sent in
+ISO-8859-1 if possible, you can set this variable to
+@code{(iso-8859-1)}. You can override this setting on a per-message
+basis by using the @code{charset} @acronym{MML} tag (@pxref{MML Definition}).
+
+As different hierarchies prefer different charsets, you may want to set
+@code{mm-coding-system-priorities} according to the hierarchy in Gnus.
+Here's an example:
+
+@c Corrections about preferred charsets are welcome. de, fr and fj
+@c should be correct, I don't know about the rest (so these are only
+@c examples):
+@lisp
+(add-to-list 'gnus-newsgroup-variables 'mm-coding-system-priorities)
+(setq gnus-parameters
+ (nconc
+ ;; Some charsets are just examples!
+ '(("^cn\\." ;; Chinese
+ (mm-coding-system-priorities
+ '(iso-8859-1 cn-big5 chinese-iso-7bit utf-8)))
+ ("^cz\\.\\|^pl\\." ;; Central and Eastern European
+ (mm-coding-system-priorities '(iso-8859-2 utf-8)))
+ ("^de\\." ;; German language
+ (mm-coding-system-priorities '(iso-8859-1 iso-8859-15 utf-8)))
+ ("^fr\\." ;; French
+ (mm-coding-system-priorities '(iso-8859-15 iso-8859-1 utf-8)))
+ ("^fj\\." ;; Japanese
+ (mm-coding-system-priorities
+ '(iso-8859-1 iso-2022-jp iso-2022-jp-2 shift_jis utf-8)))
+ ("^ru\\." ;; Cyrillic
+ (mm-coding-system-priorities
+ '(koi8-r iso-8859-5 iso-8859-1 utf-8))))
+ gnus-parameters))
+@end lisp
+
+@item mm-content-transfer-encoding-defaults
+@vindex mm-content-transfer-encoding-defaults
+Mapping from @acronym{MIME} types to encoding to use. This variable is usually
+used except, e.g., when other requirements force a safer encoding
+(digitally signed messages require 7bit encoding). Besides the normal
+@acronym{MIME} encodings, @code{qp-or-base64} may be used to indicate that for
+each case the most efficient of quoted-printable and base64 should be
+used.
+
+@code{qp-or-base64} has another effect. It will fold long lines so that
+MIME parts may not be broken by MTA. So do @code{quoted-printable} and
+@code{base64}.
+
+Note that it affects body encoding only when a part is a raw forwarded
+message (which will be made by @code{gnus-summary-mail-forward} with the
+arg 2 for example) or is neither the @samp{text/*} type nor the
+@samp{message/*} type. Even though in those cases, you can override
+this setting on a per-message basis by using the @code{encoding}
+@acronym{MML} tag (@pxref{MML Definition}).
+
+@item mm-use-ultra-safe-encoding
+@vindex mm-use-ultra-safe-encoding
+When this is non-@code{nil}, it means that textual parts are encoded as
+quoted-printable if they contain lines longer than 76 characters or
+starting with "From " in the body. Non-7bit encodings (8bit, binary)
+are generally disallowed. This reduce the probability that a non-8bit
+clean MTA or MDA changes the message. This should never be set
+directly, but bound by other functions when necessary (e.g., when
+encoding messages that are to be digitally signed).