i just tested this---you don't need to actually use a real email address. it just functions as a login.
You actually need the email address to be real because when you first attempt to sign up, there is a message that's sent to the email address for verification. You can still sign in minus verification but sometimes if you sign in from a different browser or device, the sign in could be flagged as suspicious and a verification message would be sent to your email address as I have experienced it before. Without a real email address, you won't be able to access your account (if you didn't back up your recovery phrase)
sure you can. you don't actually need a verified email for anything---it's a non-custodial wallet after all. as with any other wallet, the first thing you should do after generating it is back up the recovery phrase. the email just functions as a login username that, along with your password, decrypts your wallet. as long as you have your email/password combo, you can decrypt your wallet---you shouldn't need portis' customer support for anything.
the way i see it, providing a real email and verifying it is just leaking personal data that can be used to identify you.