Mail
 

could there be mail boxes in major cities where you can post messages and within an hour are delivered to the post box the player you have sent it to's choice of mailbox (the one they chose as their base mail box where they pick up mail) which could be the only way to communicate during an RP maybe when your Kingdom tag is on the Player list is disabled. Of course it would be Ye Olde English style writing and partchment and theres a writing gani ..