Reply to comments inside a proof directly from email

[#1]

It would be helpful to be able to reply directly inside a proof with a reply to the email notification. Currently, we can reply to an update with a comment sent as a reply to the notification email.

It's nearly impossible to tout this feature to our users without multiple comments posting outside of the proof. We'd be asking everyone to constantly differentiate between update comments and proof comments - easier for the heavy users, but not everyone falls in that category.

It's a shame because the technology of reply directly to an update is perfect for getting those non-heavy users more inclined to use the platform.