Did you figure this out? My phone is doing the EXACT same thing. It's very annoying.
I have an HTC Droid Incredible 2

 

I'm also having this problem. Anyone have a resolution yet? I'm running an HTC EVO and this is getting old quick.

 

I find that this happens everything i get a new email, read it and delete it

 

I'm having the exact same issue on my HTC Incredible 2. This is getting really old, really fast.

 

not even close to a viable solution

 

Everyone has the issue. Server side problem. So bad last night that my phone could not even keep up charging because I had vibrate on. I uninstalled for now and need to find another app until they fix it.

 

yahoo messenger is repeating incoming messages and the email is going nuts notifying me of existing emails since late last night...

 

Yep, everyone has it. Someone reviewed in the Marketplace that it was a deliberate attack on the app since it just happened to start on the same day Bartz was fired from Yahoo. Their implication was that it would force everyone to uninstall the app causing further harm to Yahoo's finances.