EWS has attachments but Attachment Collection is empty (one drive)

Question

when the email is sent from OWA browser with attachments. A link is created for attachments using one drive/sharepoint. when i tried to read the mail item from EWS the attachment collection is empty but hasAttachments flag is set to true. How do i access these attachments from EWS ?

EmailMessage message =  EmailMessage.Bind(service, item.Id, new PropertySet(BasePropertySet.IdOnly, ItemSchema.Attachments));

message.Attachments is empty

You need to show the code your using, reference attachments which is what you talking about requires that you set the requested server version to at least 2016 but you should also show the code you using the get that attachments for this to be a good question. — Glen Scales
I added code of reading attachments. I didn't see any examples of reading reference attachments. can i just read them like regular attachments? — Kumar Garapati
I've added a reference attachment sample, but something doesn't sound right you should still be getting something in the collection. if you look at the message with a MAPI editor like MFCMapi or OutlookSpy do you see any attachment objects? — Glen Scales

Glen Scales Glen Scales · Accepted Answer · 2019-08-08T00:11:45

Here is simple example of dealing with reference attachment for this to work you need to be using the latest version of the EWS Managed API from github (the nuget version won't have the correct classes).

        ExchangeService service = new ExchangeService(ExchangeVersion.Exchange2016);
        service.Credentials = new OAuthCredentials(Token);
        service.AutodiscoverUrl("[email protected]",adAutoDiscoCallBack);
        FindItemsResults<Item> fiResults = service.FindItems(WellKnownFolderName.Inbox, new ItemView(1));

        PropertySet psPropset = new PropertySet(BasePropertySet.IdOnly);
        psPropset.Add(ItemSchema.Attachments);

        EmailMessage Message = (EmailMessage)fiResults.Items[0];
        Message.Load(psPropset);
        foreach(Attachment Attachment in Message.Attachments)
        {
            if(Attachment is ReferenceAttachment referenceAttachment)
            {
                using (var client = new WebClient())
                {
                    client.Headers[HttpRequestHeader.Authorization] = "Bearer " + Token;
                    client.DownloadFile(referenceAttachment.AttachLongPathName, referenceAttachment.Name);
                }
            }
        }

EWS has attachments but Attachment Collection is empty (one drive)

2 Answers