The From/To type information isn't on ItemSchema
it's on EmailMessageSchema
. Call would look something like this:
ExchangeService service = new ExchangeService();
//login to your exchange server with credentials etc & set your service url
.....
//issue your search for a given user using EmailMesssageSchema.From
FindItemsResults <Item> results = service.findItems(WellKnownFolderName.Inbox,
new SearchFilter.IsEqualTo(EmailMessageSchema.From, "SomeUser"), new ItemView(100));