I am implementing an Outlook add-in which tracks emails on a personal web app. Currently it just allows the user to select and track a single email. I would like to extend it to manage the whole thread. I mean: I would like it to periodically scan new items inside the mailbox to automatically track the potential responses. Actually, a kind of "on-receive" trigger would be nicer, but I have not found anything about looking at the "Event-based Outlook add-in" docs.
Hoping the question is not too trivial, thanks in advance!
Outlook web add-ins work under the context of currently selected item only. So, you need to select an item to trigger an add-in. There is no "on-receive" trigger unfortunately.
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As a possible workaround you may take a look at Graph API.