Hi,
do you know what is the syntax to send a mail in UBUNTU ?
Many thanks.
Without additional packages installed, the standard email application is Evolution. It's a GUI application so it doesn't really have "syntax" as such. evolution -c mail invokes Evolution in mail mode.
To send an email message from the command line, you need to have an MTA installed. The current recommended MTA is Postfix, I believe, but any MTA should do (sendmail, exim, qmail, what have you). Usually they require a modicum of configuration before they will do what you want.