I'm designing an Outlook add-in and need to determine whether a selected message is part of a thread. Ideally, I'd also like to find related messages in said thread as well. Reading over the documentation, the conversationId property looks promising, though there doesn't seem to be a way to "get messages by conversationId."
Under the current version (1.4, non-preview) of the Outlook Add-in API, is it possible to detect that a message is part of a thread using the JavaScript API? Is it possible to then find other messages in the same thread?
ConversationId is part of the javascript API. This means that you can know the ConversationId for the Office.context.mailbox.item whose your add-in is focusing on. See documentation here
To my knowledge, there is no way to retrieve all mails for a given ConversationId using vanilla javascript and Office.js.
However, you may be interested in my answer here.
When something is not available with Office.js api for an Outlook Add-in you can try to use the Exchange Web Services (EWS) or REST APIs to perform the action
You have basically two ways to request EWS from a mail add-in.
- You can request directly the EWS with a SOAP request from your client app. See method makeEwsRequestAsync in Office.context.mailbox(https://dev.outlook.com/reference/add-ins/Office.context.mailbox.html).
- You can get an access token, send it to your server and make the request from there.
For the specific case of retrieving conversations using the Outlook REST API, this answer may also be helpful.