Messaging suggestion

The IM system could really use a change in regards to spam prevention. The 20 second limit might be a decent deterrent, but what if instead there was, for example, a 3-message limit with another user before they respond and an overall limit of starting 2 new conversations per hour? It seems like it would be more conducive to using messages as an IM system to not have a 20 second cooldown when talking to the same person.