Stop
1) Yahoo constantly changes things around, this is very frustrating.
2) Stop changing things that already work (e.g., what is the silly dark blue background that is there when I read a news piece - some parts of the write-up are hard top see now, there are many more examples).
3) Work on fixing the problems (the e-mail piece, especially changing fonts, editing, ..., needs a lot of fixing). I am getting so tired of these issues that I am considering to ditch Yahoo and start fully using ....
4) Get people who have more logic (or at least some good logic and a lot of common sense) to work and upgrade your offerings. The way you are going (frustrating your users), will certainly lead to loss of clients.