It seems that you are looking for a DLP (data loss prevention) solution.
I'm not sure that Ironmail would be the right fit for this. I do know there is some sort of DLP capability but I don't know the extent of the feature set.
Setup a regular expression for outbound mail to match that criteria as well as turn on HIPPA dictionary .
Thats a large dictionary and I would not suggest its use on a 6.7.2 appliance.
MEG7, which is due to be released sometime Q4, will have DLP built in to it, however with 200k entries it may still be quite a bit for a box to handle, unfortunately there just isnt any information on its capabilities yet.
As of right now, I do not believe there is an upgrade path from 6.7.2 to 7.0, so it would require a re-image.