workflow not sending email notifications

The problem actually started yesterday when the unix admin was working on a secondary zone and rebooted. It supposed to be not affecting the first zone where the EBS resides on, but unfortunately it did. The server ran out swap space and the system throws ora-04030 process memory error. For a short while, we cannot even log on. Later on, when the swap space come free and we are able to log back in to the EBS system. However, the workflow mailer would not want to send out emails. I have tried send test mailer to my email box but