I just created a search folder the other day that did the same thing, using the example from the How to: Work with search folders by using EWS in Exchange topic:
// Create a search filter to express the criteria
// for the folder.
EmailAddress manager = new EmailAddress("sadie@contoso.com");
SearchFilter.IsEqualTo fromManagerFilter =
new SearchFilter.IsEqualTo(EmailMessageSchema.Sender, manager);
Now this is using the Sender property, not the From property. I think you could simply replace one for the other, but I didn't test to be sure.