This is not a Yahoo problem only. I have the same problem with both of my 2G Iphones - one using the Yahoo mail server and the other using the GMail server.
I too have observed that it seems to be related to marginal/intermittant signal strength. The best guess I have is that this is a flaw in the logic of the Iphone email software when dealing with weak/intermittant connections.
I too have observed that it seems to be related to marginal/intermittant signal strength. The best guess I have is that this is a flaw in the logic of the Iphone email software when dealing with weak/intermittant connections.