ConversationId property vs ConversationIndex property in Exchange Web Services managed API

Question

EWS Managed API have two properties:ConversaionId and ConversationIndex

What is the difference between them? I guess ConversationId is the the Con

Answer 1

It should be noted that ConversationId does not appear to be unique per entirely different conversation threads.

Meaning, while you can be assured that two conversations that don't share the same ConversationId are definitely not related, the converse -- that the same ConversationId guarantees the same "email thread" -- as popularly understood (people answering each other in a chain) -- does not appear to be the case.

I have discovered multiple instances of the same ConversationId on the same email Subject (every now and then) even though the cascade is not off the original.

So for example if HR sends out a "Thought of the Day" email freshly each day to a given group X, this may have the same ConversationId even if they are new chains.

This is problematic if one is sorting emails on a website from payroll by, say, "RE: your 401k" and two distinct conversations are conflated.