The Android mail client has a problem that no one is admitting. Periodically, the app can't connect to the mail server and reports that the username or password is incorrect. After hours and sometimes days, it reconnects as if there was never a problem. Gmail has no problem. It uses a separate app. Every other mail I know, not just Yahoo, has had this problem. Yahoo has it often. iPhone, iPad and iPod mail clients never have this problem. Therefore it has got to be the Android app. Why doesn't someone own up to facts and either fix it or at least admit the problem is too difficult for them to fix.