Marcus,
In order for DLP to even look at the meta tags you will need to enable this functionality on EACH of the detection servers.
Go to the Server Settings page for the DLP Endpoint server and change the following setting to TRUE
ContentExtraction.EnableMetaData = true
You will need to recycle the Services.
This will allow the server to extract the meta tags to match for the keywords you are looking for.
Good luck
Ronak
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