I have done a bit of searching and am unable to find a list of legal properties for use with the FindItem <Restriction> element, specificially what can I use in
<IsEqualTo><FieldURI FieldURI="???"></IsEqualTo>that will not result in a ErrorUnsupportedPathForQuery error?
(Using EWS Exchange2010_SP1)
I wrote an integration test which performs a FindItem using an exists filter for each of the UnindexedFieldURIType. Sorry private project, can't post code.
These fields work:
It's worth noting that of the fields that produce an error, most fail with an ERROR_UNSUPPORTED_PATH_FOR_QUERY, but others fail with a ERROR_INVALID_PROPERTY_FOR_EXISTS. That suggests that some fields work with some some SearchExpressionTypes while others don't.