To send mail to another user or to a mail list, you use the @send command.
@send <*list-name or user>
This command form will prompt you for the text of the message and the subject and then send the mail message to the specified mail list or user.
Note: In the near future, this command will gain a few options to allow it to drop you into an editor and to support CML based mail messages.
@send <note> to <*list-name or user>
This command form will allow you to send the text of the note to the specified mail list or user.