DoRequest.cs

public void DoRequest(IOrganizationService service)
{
    var request = new OrganizationRequest("ResolveEmailAddress");
    request.Parameters["EmailAddresses"] = "test@test.com";
    request.Parameters["ObjectTypeCodes"] = new int[] { 1, 2 };

    var response = service.Execute(request);
    if (response.Results.Contains("Entities"))
    {
        var result = (EntityCollection)response.Results["Entities"];
        //go nuts with the result
    }           
}