Google captures enormous data from Gmail which it uses in optimizing other products.
Smart Compose & Smart Reply allow you to quickly write emails with minimal or zero typing.
Google basically understands how you compose emails and help you write them faster.
This boost in email drafting productivity is unmatched today and will “act as a gateway to sell more Gmail for business packages to enterprise customers”. – Pen Magnet
Reference: https://link.medium.com/th5uoXrxe6
Prashant Bagga 