They’re intended to work and look like your usual Discord or similar emoji reactions, as long as it’s between Gmail users:
To non-Gmail users, those reactions would appear as regular email replies with a big emoji:
I don’t know how to feel about it personally, it’s the kind of feature that seems completely detached from reality as that’s certainly not how most people use emails, and the only thing it will create is more email garbage filling up your inbox.
EDIT: The person who found about the feature first (assembledebug) also added how to enable it:
Ben forgot to mention how it can be enabled 🙂 ?
You need a rooted phone and need to flip a switch of a flag using GappsMod.
Just use K-9 mail or other email clients, no one’s forcing you to use Gmail.
I will try it out!
I originally used MyMail as an alternative to Gmail, but when i eventually discovered it’s garbage collection was even worse than Gmail’s, i switched back.