Ever since we launched comments, Buttondown has emailed you when a subscriber comments on one of your posts, and emailed your subscribers when someone replies to their comment. But those notifications were read-only: to actually respond, you had to click through to the archives and type your reply there.
Such hoops of indirection are a thing of the past! Every comment notification now accepts replies. Hit reply in your email client of choice, write what you have to say, and send — your response threads right back into the discussion, attributed to you, and the other party gets notified just as if you'd written it on the web. This works for you as the author and for your subscribers alike, on every plan with comments enabled, with no setup required.
I could tell you something lofty and business-brained about how this makes it easier and more wonderful for you and your subscribers to continue conversations on the go, or whatever. But mostly I just think it's neat when email is used as an interface and not just a broadcast mechanism, and this felt like an obvious such example where we could improve.