`/usr/lib/sendmail` if such program is available, or
`localhost` otherwise.
+--smtp-server-port::
+ Specifies a port different from the default port (SMTP
+ servers typically listen to smtp port 25 and ssmtp port
+ 465).
+
--smtp-user, --smtp-pass::
Username and password for SMTP-AUTH. Defaults are the values of
the configuration values 'sendemail.smtpuser' and