I cannot emphasize this enough, if you've ever used Twitter credentials to log into anything else you need to figure out how to get out from under that as soon as you can.
@mhoye Good reason why people shouldn't rely on centralised signin. I bought my own domain and found an email host that allows for easy migration (Migadu) and I now use various aliases with generic addresses to sign up to stuff. If Migadu goes down, I still own the domain, so all I have to do is point it at a different server. And if my domainregistrar goes under, I can transfer my domain to another registrar. It's also cheap at ~12$ a year for the domain and 19$ per year for email.
Ofc, cheap is relative. But to me it's worth it to not be locked into a centralised system.