The variable @code{send-mail-function} controls how the default mail
user agent sends mail. It should be set to a function. In most cases,
the default is @code{sendmail-send-it}, which delivers mail using the
-Sendmail installation on the local host. On Mac OS X and Windows,
+Sendmail installation on the local host. On Mac OS X and MS-Windows,
however, the default is normally @code{mailclient-send-it} (see
@file{mailclient.el}). To send mail through an SMTP
server, set @code{send-mail-function} to @code{smtpmail-send-it} and set