Outgoing email stopped working

I am running RT with POSTFIX and SENDMAIL. Due to some other activity
the / partition became full. After I cleared the problem, RT started
working again. However no outbound email is sent when tickets are
updated. Inbound emails are received and update the tickets fine. I have
tested sendmail and postfix and everything is working fine on this
server RT is the only application with this email issue. Any
suggestions?

Thanks,
James