fail to send an email

Hi everybody,
I tried to send a message from my PC to my abelahcene@gmail.com, using mail command from terminal like this

aminati@debian:~$ mail bela@debian
Subject: hello abi
hello abi
.
Cc: abelahcene@gmail.com

The message to local correspondant is delivered, while the remote one is not . I have the standard installation of lenny, with exim4 running??
Do I need to stop exim4 or to configure it ?

Here is the error :

From MAILER-DAEMON Tue May 05 19:13:43 2009
Envelope-to: aminati@debian
Delivery-date: Tue, 05 May 2009 19:13:43 +0100
X-Failed-Recipients: abelahcene@gmail.com
Auto-Submitted: auto-replied
From: Mail Delivery System <Mailer-Daemon@debian>
To: aminati@debian
Subject: Mail delivery failed: returning message to sender
Date: Tue, 05 May 2009 19:13:43 +0100

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

abelahcene@gmail.com
Mailing to remote domains not supported

------ This is a copy of the message, including all the headers. ------

thanks for help
best regards
bela