Adding and inviting friends offline (cross-server friends)

[Ambacht]

I'm unsure if this has been suggested before, if it has then sorry.

Recently I have been to gamescom and had a blast, I even met a few people from my own server.
The thing is that we can only invite each other when we are both online,
why can we not just send a friend request when they are offline so they can accept when they come online?
This makes it more easy to connect with people.
Another is to connect with friends cross-server (on the same data centre) so you can interact in-game even though you don't play on the same server.
I hope you like my idea and let me know what you think of it.

Kuro Kenshi