Please check the WF Mailer log.
Dear Mr. Bashar
please more details
Check if the Workflow Notification mailer is running or not. Go to System Administrator --> Workflow --> Service Components. If its not running start it or configure it properly if required. Check the Workflow logfiles in $APPLCSF/$APPLLOG directory.
Check also if the applmgr (Application OS user) is able to send mails using mailx etc.