The requested web method is unavailable to this caller or application thrown when using `GetConversationItems`

Question

In my outlook web add-in I use Office.js's getCallbackTokenAsync to get the token before connecting to EWS in my asp.net back end.

ExchangeService service = new ExchangeService();
                service.Url = new Uri(mailItem.ewsUrl);
                service.Credentials = new OAuthCredentials(mailItem.ewsToken);
                PropertySet ps = new PropertySet(
                                                ItemSchema.Subject,
                                                );
                _email = EmailMessage.Bind(service, new ItemId(mailItem.itemID),ps);
//the following throws error
    ConversationResponse response = service.GetConversationItems(convId,
                                                                 properties,
                                                                 null,
                                                                 foldersToIgnore,
                                                                 ConversationSortOrder.TreeOrderDescending);

Seems like this GetConversationItems method is not allowed when I used the token retrieved by Office.js to initialize the EWS service. I tried to updated the manifest permission to the highest level to ReadWriteMailBox but still not working. Seems like I can only use Office.js to call EWS ?

Answer 1

The token you get from getCallbackTokenAsync is only used to retrieve attachments on the current item or on the current item. For more information, please see the following link:

getCallbackTokenAsync

Best Regards,

Evan