Thank you for the answer. Its interesting to see what people would use these things for. The reason being, often you may be asking for the wrong things. Just from the above, you arent actually looking to validate all accounts. What you are actually looking for is to flag those 2 scenarios.
The first one for example, might be worth a different suggestion, as what you are actually asking for there, is to have it flag when a user starts showing from a different country.
The second, you should already be able to do. If there is a pattern in the structure of an email address, you can simply ban that structure of email address