Bitmessage is essentially a floodfill algorithm. You just need to request neighbor list from your neighbor which delivered the message to you before others. The

Bitmessage is essentially a floodfill algorithm. You just need to request neighbor list from your neighbor which delivered the message to you before others. Then, you connect to them and you are one step closer to the sender. Repeat it until you are connected to the original sender and all its neighbors. So Bitmessage does not protect you if you use the same sender identity multiple times.