Google has announced an update to Gmail at their I/O event recently called 'Smart Replies' where Gmail creates automated responses based on the emails content and your writing style. These automated responses will be listed as options at the bottom of an email that you've been sent. You pick one of the responses listed and can then either send it immediately or modify it to your liking.
This new tool is great for people who simply have far too many emails to type out an individual email to every single person. Especially shorter emails which don't really require any thought, or for people who can't get their inbox down to 0.
The feature will be rolling out globally on Android and iOS for English speaking countries first and will then be added to Spanish speaking countries in the coming weeks Google have said, with more languages in the works.