Variable: utf7-imap-direct-encoding-chars
utf7-imap-direct-encoding-chars is a variable defined in utf7.el.gz.
Value
" -%'-*,-[]-}+\\~"
Documentation
Character ranges which do not need escaping in the IMAP variant of UTF-7.
Source Code
;; Defined in /usr/src/emacs/lisp/international/utf7.el.gz
(defconst utf7-imap-direct-encoding-chars
(concat utf7-direct-encoding-chars "+\\~")
"Character ranges which do not need escaping in the IMAP variant of UTF-7.")