Thanks a lot for the reply. In fact I guess, this is not exactly what I wanted to do. I would like on different step of a workflow be notified by email. It seems that the system does not use the message text we are setting in the notification tab on the workflow configuration but it is using the email template setup in Basic-->Setup-->Email template.
The issue is that I would like in the message body information on step (Started, Rejected, Approved, delegated, cancelled,and also PREQ number ...). I tried to used %<TableName>.<FieldName>%, but it does not works and I don't understand how using the same email template how I can get information on the Workflow step. I don't understand neither why the Message text setup in the notification tab of the workflow and used to send the notification in the client (popup and notification windows) is not used for the email.
PS : Thanks a lot for your quick answers, I just discovered this web site today and I have to admit I am quit impress by the quality of your answers.