Transport Rule Text Pattern Exception

One of my customers is using Exchange 2010 transport rule to block users from sending e-mails with social security number pattern 123-45-6789.  They have recently ran into trouble with a filing system that uses the format AB123-45-6789.  They still want to block ###-##-#### without blocking XX###-##-####.  I thought that this would be a one minute job but that wasn't the case, for some reason, the transport rule did not respond the way I expected it to.  

Here is my rule

If the message:

    Is received from 'Joseph.Durnal@exchangelab.info'

    and Is sent to 'Outside the organization'

    and Includes these patterns in the message subject or body: '\d\d\d-\d\d-\d\d\d\d'

Take the following actions:

    reject the message and include the explanation 'Caught SSN Pattern'

with the status code: '5.7.999'

Except if the message:

    Includes these patterns in the message subject or body: '\D\D\d\d\d-\d\d-\d\d\d\d'

Any idea why this wouldn't work?

Thanks,
Joe

Joseph M. Durnal MCM: Exchange 2010 MCITP: Enterprise Messaging Administrator, Exchange 2010 MCITP: Enterprise Messaging Administrator, MCITP: Enterprise Administrator