What happens when email tied to TW acct is suspended?

I could swear I asked this, but I don't see it anywhere. Must've been one of those times system flagged me for "soliciting"

Anyway, what happens if the email used to verify a TW acct is suspended? TW returns it's notices as undeliverable, right? What then? Does TW demand phone verification? Suspend account?

I read somewhere that some of the email providers do things like sell the same emails multiple times, or maybe keep using the same proxies 'till they get banned by gmail or similar... so maybe they do somethign that gets it shut down, or maybe acct is just suspended since I haven't logged in in a year or two. In any case, what does TW do when the email is no longer good?

I'm 100% positive you can't use the email with the suspended account tied to it again

I guessed as much. So is this happening to people who have purchased emails in bulk? If so, is it the result of them doing things wrong, or can it happen simply because you never log into it any more? If so, which email providers?