this was already designed by @therealwolf several years ago. But the point why it was given up is because messaging does not belong on a blockchain (it is completely inferior to off chain services as well; e.g., no private messages, no deletion capability etc.). It is also a waste to Hive's resources...
You should read up on beechat:
Some details on this messaging system and BeeChat:
PeakD uses an external chat system called BeeChat developed by @aggroed and @reazuliqbal. Read more HERE.
BeeChat verifies the identity of Hive users validating the signature of a short message
BeeChat is integrated on multiple websites, not just PeakD
Presently BeeChat is NOT encrypted. Please be careful with what you share using this chat system (until there is a solution to improve upon this)
It is a new system still in development and we can expect that there will be more features available in the future