There is one called 3jam but I'm not sure how good it is because I have't tried it yet. I have heard good and bad. Here's the link if your interested...
One of my major gripes on the BB. I also find it silly that you can't just keep the last message in a convo which includes all previous ones.
It actually deletes chunks. Considering how BB is the messaging King this is a huge oversight, imho.
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