Database Mail : Mail Not queued DBMAIL is stopped....

Hello

I tried for hours to get my Database mail work, without success, on SQL Server 2005 ent Edition 64bit SP3 in cluster environment

I send mail with the test :
USE msdb

GO

EXEC sp_send_dbmail @profile_name='SQLDBA',@recipients='mai@mail.tld',

@subject='Bonjour ',@body='Congrates Database Mail Received By you Successfully.'

But this mail seems to be never sent.

With:

EXEC msdb.dbo.sysmail_help_queue_sp @queue_type = 'mail';

The queue state is always INACTIVE,

I tried to restart the mail system some times :
EXEC msdb.dbo.sysmail_stop_sp;
EXEC msdb.dbo.sysmail_start_sp;

I tried to restart of SQL Agent,
The broker is activated (SELECT is_broker_enabled FROM sys.databases WHERE name = 'msdb' ;),

Event Viewerlogs:The activated proc [dbo].[sp_sysmail_activate] running on queue msdb.dbo.ExternalMailQueue output the following:'the service queue "EXTERNALMAILQUEUE"'is disabled.

With this i STARTED with EXEC msdb.dbo.sysmail_start_sp;
and also alter queue EXTERNALMAILQUEUE with status on, But in 10 15 secs it again gets STOPPED.

I tried a msdn topic for:Troubleshooting Database Mail: Send mail from remote server when troubleshooting local server.below is the link given.
http://msdn.microsoft.com/en-in/library/bb326746%28v=sql.90%29.aspx

But above also dint worked for me.

Please help me getting out of this issue.

Regards,
AShish