Buttondown Documentation
By default, when you send out an email to your subscribers, the email address to which folks can reply is your email address, meaning that any subscriber who hits "reply" on their email client will send an email straight to your email address.
This is totally fine for most use cases, but sometimes you want to be able to manage replies in a more sophisticated way: maybe you want to track which emails received most replies, or trigger automations based on who's replying, or forward replies to other members of your newsletter. For that, Buttondown offers tracked replies.
You can enable tracked replies on a per-newsletter basis in the Tracking settings page.