Sounds like you're just getting locks and not bans. It's pretty common right now. If you're really invested into the accounts you can try to unlock them, otherwise just make a new one.
It has to support a catch-all or mail forwarder to route all emails to a single inbox, we've tested with a couple different providers so far with no issues.
You can use Farmaton to automate the creation and tutorial process. And then just go register the email domain yourself if you don't want it tied to your own private mail domain
You could use a domain that doesn't require many personal details to register, and just create accounts with addresses that don't exist yet on that domain. If the account lasts long enough to not get banned, you could register the address and provide all of the details to the buyer maybe?