+@vindex rmail-file-coding-system
+ When you get new mail in Rmail, each message is translated
+automatically from the coding system it is written in, as if it were a
+separate file. This uses the priority list of coding systems that you
+have specified. If a MIME message specifies a character set, Rmail
+obeys that specification. For reading and saving Rmail files
+themselves, Emacs uses the coding system specified by the variable
+@code{rmail-file-coding-system}. The default value is @code{nil},
+which means that Rmail files are not translated (they are read and
+written in the Emacs internal character code).
+