Search by category Exchange Server EWS

Question

I need to get all the emails that have a specific category name, how would I do this?

Right now I have this:

var col = new List<SearchFilter>();
col.Add(new SearchFilter.ContainsSubstring(ItemSchema.Categories, "Processed"));
var filter = new SearchFilter.SearchFilterCollection(LogicalOperator.Or, col.ToArray());

FindItemsResults<Item> findResults = service.FindItems(
    WellKnownFolderName.Inbox,
    filter,
    new ItemView(10)
);

But that gives me a Microsoft.Exchange.WebServices.Data.ServiceResponseException that says {"The Contains filter can only be used for string properties."}

How would I do it?

Answer 1

AFAIK as of Exchange 2010, category is a multi value field so it does not work with search filters. However, you can search categories using AQS. The following code should do the trick.

ExchangeService service = GetService(); 

var iv = new ItemView(1000);
string aqs = "System.Category:Processed";
FindItemsResults<Item> searchResult = null;
do
{
    searchResult = service.FindItems(WellKnownFolderName.Inbox, aqs, iv);
    foreach (var item in searchResult.Items)
    {
        Console.WriteLine(item.Subject);
    }
    iv.Offset += searchResult.Items.Count;
} while (searchResult.MoreAvailable == true);   

Answer 2

I use the following code, to find all messages, which do NOT have set the category "Processed" and which have been received after a given date.

                SearchFilter sf = new SearchFilter.SearchFilterCollection(LogicalOperator.And,
                                   new SearchFilter.Not(new SearchFilter.IsEqualTo(EmailMessageSchema.Categories, "Processed")),                                       
                                   new SearchFilter.IsGreaterThan(EmailMessageSchema.DateTimeReceived, minDate));