Portal service to notify on user account locked

Hello All,

We have a Portal 7.01 environment. I am working on a requirement where I need to get an email sent out to the team as soon as the user account is locked. After looking into various posts I think this can be achieved by developing a Portal service which implements one of the UME interfaces. I can find PrincipalListener and PrincipalAttributeListener interfaces of UME APIs but not sure which one I can use to trap the account lock.

Please suggest how I can achieve this or how I can implement this.

Thanks,