No instant mail system but...

[Stone Dog]

...I think it would be even cooler if you're able to intercept and kill those couriers just to disturb people's mail or to gain intel about the opponent.
But if you implement something like that how easy should it be to catch and kill them? That's pretty difficult to calculate honestly.
It all depends on the route they take, how big the world is and how much people are playing. Because I wouldn't send mail to someone if it has a 5% or more failure rate...

Interesting thought here. Of course if this was implemented then would people bother sending sensitive materials in the mail if there was even a 1% chance that it could be "re-routed?" I have some jumbled thoughts on the topic and if they ever settle into a coherent idea I'll post it here...but that may be asking a lot.

[master]

But if you implement something like that how easy should it be to catch and kill them? That's pretty difficult to calculate honestly.
It all depends on the route they take, how big the world is and how much people are playing. Because I wouldn't send mail to someone if it has a 5% or more failure rate.

Just send a bunch of birds. If each bird has a twenty percent chance of failure than sending three or four messages would probably mean that at least one gets through.