How can I set tax exempt status based on email extension?

[WildThingsNick]

Any insight on how to achieve this is greatly appreciated. We've reviewed a number of extensions and stock capabilities with no luck. Thanks in advance!

Looking to create a rule/filter that sets customer tax status to exempt/excluded based on their email extension - there are three specific TLD extensions that we want to have exempt/excluded status within our store. Creating customer group filters based on email domain does not work as there are too many domains and subdomains associated with these extensions and we cannot/do not know all of them. But, all would qualify with the three specific extensions. 

Example:
name@subdomain.domain.ext - specifically looking to create the rule around the 'ext' part

This would apply to customer checking out as guests, as well as logged in - neither should be required.

[sweetcw]

This would be valuable

[Zhopify]

Did anyone figure out a solution for this?  Possibly with a Shopify Flow?