msmtp - msmtp is an SMTP client.
blat - Blat is a small, efficent SMTP command line mailer for Windows.
sSMTP - sSMTP is a simple MTA to deliver mail from a computer to a mail server.
CMail - CMail is a free Windows command line mailer with advanced message formatting options.
Postfix - Postfix is a mail transfer agent (MTA) that routes and delivers electronic mail.
sendEmail - sendEmail is a lightweight, command line SMTP email client.