I'm imagining some sort of proxy address that everything has to be sent through, with ATTN: [Player Name] being used to indicate the recipient. And for an added bonus...the messages that are passed along might be partially [REDACTED] by the proxy.... ;)
I was thinking about this aspect, and the first thing that popped into mind was the Hogwarts letters from Harry Potter. So imagine a mail-in game (I'll just call it a MIG?) where all the players are remote-learning "students" in an academy. All coursework and correspondence is handled through the mail for some as-of-yet undetermined plot reason. :P That setting gives you a lot of parallels to draw from for inspiration. (Grades for progress, assignments...)
Concept in progress, I'll post more after I've given it more thought. :)
