Oh, I've always loved these emails that have interactivity built in. Specifically, I have thoroughly enjoyed emails that I get from Google Docs that shows the edits that other people have made on the document that I shared with them. It gives me the option of commenting and submitting my comment there itself. This has been an extremely solid user experience.

While I know that since Gmail is a Google property and that kind of experience cannot be delivered by emails sent by others, I've often wondered why other products haven't used this functionality as much.

Curious to see what all can be done.

Can anyone share examples of other products doing this really well?