Documentation can be found at http://tcllib.sourceforge.net/doc/smtp.html
Here's a minimal useful example:
proc send_simple_message {recipient recipient_server subject body} { package require smtp package require mime set token [mime::initialize -canonical text/plain -string $body] mime::setheader $token Subject $subject smtp::sendmessage $token \ -recipients $recipient -servers $recipient_server mime::finalize $token } send_simple_message [email protected] starbase.neosoft.com Oh-ho! \ "This is the message."
Category Package, subset Tcllib