+=item B<-starttls protocol>
+
+send the protocol-specific message(s) to switch to TLS for communication.
+B<protocol> is a keyword for the intended protocol. Currently, the only
+supported keywords are "smtp" and "pop3".
+
+=item B<-engine id>
+
+specifying an engine (by it's unique B<id> string) will cause B<s_client>
+to attempt to obtain a functional reference to the specified engine,
+thus initialising it if needed. The engine will then be set as the default
+for all available algorithms.
+
+=item B<-rand file(s)>
+
+a file or files containing random data used to seed the random number
+generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
+Multiple files can be specified separated by a OS-dependent character.
+The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
+all others.
+