sending mail from the command line

[Dan Shimshoni]

I am trying this from a Linux machine which is connected to the
internet via PPPoE ( for the test, no firewall):
 mail -s "test" danshimsh at gmail.com < /dev/null

and also this
 mail -s "test" danshimsh at gmail.com
enter
add some text
enter
ctrl-d


I don't get any mail in danshimsh at gmail.com.

What is wrong here ? what should I do in order to send successfully an
e-mail from the command line with "mail" ?

DS