Google engineers gave a few hints about where the new Gmail interface, Inbox, is headed in a Reddit AMA on Wednesday. One interesting upcoming feature — aside from support for browsers other than Chrome — is an Undo Send feature that was apparently being worked on but narrowly missed the launch date. How would unsending an email work? Well, if you’re an Inbox user sending a message to another Inbox user, it could conceivably rescind messages that have already been delivered (like BBM does). But more likely it will work like the popular undo send feature from Google Labs, which gives you up to 30 seconds after you press “send” to realize you’ve made a mistake.