Weird kex_exchange_identification error

sshd
error: kex_exchange_identification: client sent invalid protocol identifier "CONNECT hotmail-com.olc.protection.outlook.com:25 HTTP/1.1"

This line appears in logs 2-3 times per month, simply explained I really don't have a clue what's causing it. It's a testing machine with Ubuntu 20.04 LTS running nginx + php + wireguard + cockpit, nothing more


The internet is full of bots trying to find anything to abuse.

This case looks like a bot that is trying to find an open HTTP proxy and use it to connect to Hotmail's SMTP servers.