Title is pretty self explanatory: What is your e-mail provider? If you've more than one, state them all! Mod note: Creating an AirVPN account does NOT require a valid e-mail address.
Tutanota seems to be a very fickle email provider. My account was closed at the beginning of this year without any warning. I used this account with minimal activity, so there was no harm with their action. Similar story happened with another user:
I'd recommend (in addition to protonmail & posteo) https://disroot.org/en https://countermail.com/