There's not much documentation on those two programs, I think.
To get basic help (builtin), type
sendmail /?
You'll get some information on the commandline parameters. Having seen
how the Unix-version of sendmail works I had no problem to send mails
with both versions.

The SMTP version supports input redirection, the first line of the
message file to send should be a blank line.
sendmail -s "My subject" -t my.smtp.server -f me.anywhere.com
receiver.elsewhere.com < preparedmessage.txt

Regards,
Michael
--
Michael H. Bartl
Michael H. Bartl
ADAC e.V. (Rechenzentrum, Produktionsplanung und Organisation)
Tel.: (089) 7676-4063, Fax: (089) 7676-8161
EMail: Michael.Bartl AT Zentrale.ADAC DOT de