Gmail for Android is finally getting the Undo button- a feature that is present on the desktop site. The Gmail for Android V8.7 can now undo sent emails and this allows you to have a few extra seconds to quickly reverse the message and add anything that you might have missed.
However, this might actually be a server-side rollout, as it wasn’t present until the Gmail app is force killed or swiped out of memory. The implementation of Undo is quite identical to how things were in the Inbox app. When you send an email, now you’ll get a notification at the bottom of the screen. Once you tap the undo button, you will be taken back to the drafting screen for the applicable email.
Once the time to undo is passed, you can still stop the recipient from getting it, given that it is for Gmail-to-Gmail emails. Either way, tap the “undo” prompt, and the email won’t be seen by the recipient. But since it is a server-side rollout, there’s no way to tell when the feature would be available to everyone. You can try by downloading the latest V8.7 app from here.