Sign in using your mobile phone number instead of your email address. Then go to your account setting to update your email address. (It might help if you've got a 'spare' email address available to change to if the troublesome one is already shown in your account settings. You can then try changing to the 'spare' and, if you so wish, back again to the original address. If you need somewhere to create such a spare address, go here:
https://www.gmx.co.uk )