I had the same issue for a week + and the resolution was changing my password to one that included ONLY numbers and letters - no special characters. You'll do this on the Verizon side, but it should allow you to access your email on the Yahoo side. I don't know if it's a temporary glitch or some long-term issue on the Yahoo side, but they aren't recognizing special characters - that's what's causing the invalid password error on the Yahoo side.