Apparently Microslop allows LookOut users to "like" a mail. It then sends out a mail with a thumbs up emoji (and $person reacted to your message).

Most useless feature I have seen in a long time and incredibly frustrating to be on the receiving end.

@h3artbl33d have had to use 365 at a client for a few weeks and it is annoying. Even Outlook thinks its bad, it marked the digest mail of reactions from co-workers as spam