XenForo already has an email domain blacklist. I suggest to also add a whitelist. And an admincp option to moderate registrations with new email domains.
At first it takes a little work to build up a whitelist, but once the whitelist is filled, then a very small fraction of registrations get moderated and its 95% problematic accounts.
- When a user registers with an unknown email domain, send the registration to moderation.
- Display the unknown domain in the moderation queue and link it to a google search for the domain. This will allow the admins to find out if the domain is legit or a temp/fake mail.
- Display an option in the moderation queue to 'Approve & add to the white-list'
- Display an option in the moderation queue to 'deny and add to blacklist'
At first it takes a little work to build up a whitelist, but once the whitelist is filled, then a very small fraction of registrations get moderated and its 95% problematic accounts.