I understand security is important, but every gd time is nuts. Get some programers that have a clue what they are doing.
Use an authentication word, don't force people to use another email address to login. ONCE a day is sufficient not every time. NO ONE trusts Yahoo enough to give you a cell phone number so stop asking. Develop trust over time first. Stop with the worthless program changes.If you want to add a useful feature ok, but leave the stupid "move stuff around so people will think its improved" to Microsoft we are used to that.