+Regexp matching alternative email addresses. The first address in the
+To, Cc or From headers of the original article matching this variable is
+used as the From field of outgoing messages, replacing the default From
+value.
+
+For example, if you have two secondary email addresses john@@home.net
+and john.doe@@work.com and want to use them in the From field when
+composing a reply to a message addressed to one of them, you could set
+this variable like this:
+
+@lisp
+(setq message-alternative-emails
+ (regexp-opt '("john@@home.net" "john.doe@@work.com")))
+@end lisp
+
+This variable has precedence over posting styles and anything that runs
+off @code{message-setup-hook}.
+
+@item message-allow-no-recipients
+@vindex message-allow-no-recipients
+Specifies what to do when there are no recipients other than
+@code{Gcc} or @code{Fcc}. If it is @code{always}, the posting is
+allowed. If it is @code{never}, the posting is not allowed. If it is
+@code{ask} (the default), you are prompted.
+
+@item message-hidden-headers
+@vindex message-hidden-headers
+A regexp, a list of regexps, or a list where the first element is
+@code{not} and the rest are regexps. It says which headers to keep
+hidden when composing a message.
+
+@lisp
+(setq message-hidden-headers
+ '(not "From" "Subject" "To" "Cc" "Newsgroups"))
+@end lisp
+
+Headers are hidden using narrowing, you can use @kbd{M-x widen} to
+expose them in the buffer.
+
+@item message-header-synonyms
+@vindex message-header-synonyms
+A list of lists of header synonyms. E.g., if this list contains a
+member list with elements @code{Cc} and @code{To}, then
+@code{message-carefully-insert-headers} will not insert a @code{To}
+header when the message is already @code{Cc}ed to the recipient.