Finding mail messages with no categories set?

Question

Hi

Is there any way I can do the following:

1. Using the $filter option only find emails that have no categories set.
2. Using the $search option only search for emails that have no categories set.

Thanks
Ward

Answer 1

You can do it using and Advanced query with filter https://learn.microsoft.com/en-us/graph/aad-advanced-queries?tabs=http eg

$filter=NOT(categories/any())&count=true  

or with the Graph SDK

            var queryOptions = new List<QueryOption>()  
            {  
                new QueryOption("$count", "true")  
            };  
            var uncatMessages = graphClient.Me.MailFolders["Inbox"].Messages.Request(queryOptions)  
                .Header("ConsistencyLevel", "eventual").Filter("NOT(categories/any())").GetAsync().GetAwaiter().GetResult();  

2. With Search that uses Content index's and KQL so AFAIK you can't search for a null value in a content Index or for the number of values of property in a Index, you could use 'not' in KQL to find message that don't have a particular category value set.