TIL: IP address is a legit part of email address!
You can (theoretically) send a message e.g. to user@1.1.1.1 (and maybe even @1.1?)
Imagine also IPv6 was a real thing and we could send messages directly to any device. P2P email... I wonder if that could work out 
For boring details, see https://www.serviceobjects.com/blog/ip-address-vs-domain-in-an-email-address/
The current one is tunneled. Overall https://www.google.com/intl/en/ipv6/statistics.html#tab=ipv6-adoption
@bemyak
@L29Ah Sorry, what I meat is that you can't assume that a random person will have it. Many providers simply refuse to deal with it, unfortunately.
How did you get yours? Was it given by default or did you request it specifically?