I know it may be a while away, but this links to What is the Upgrade plan of the Comments feature?, having emails as a Thread View would be absolutely beautiful. I know thread view is only for entity comments right now, but why not extend it further to any entity types? (Or upgrade comments to proper entities 
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Thread view is beautiful for commutation for things like email, integrated chat, think integrating whatsapp api to fibery, or any other communication platform. Curious to hear your thoughts.