I needed a "throw away" email address a few weeks ago for a short period of time.
As I already use Gmail, on android and laptop, I chose Hotmail to avoid any conflict with cookies, two accounts etc.
It was a nightmare from start to finish, Hotmail wouldn't sync for days, emails not sending.
Perhaps the best option would be to start fresh with a different email provider (GMail) and update your details on the sites you are having problems with?