I am working on rebuilding old Magento 1 shop to Magento 2.
There was an extension CRM EmailExtractor, which was used to extract email, firstname and secondname of customers under determined criteria (i.e. emails of customers, that bought something in January or have lifetime sale more than 100$).
Hello, I'm not sure but it seems to me that Customer Segmentation is similar to your extension. I use it for my store to determine email adresses depending on set rules. And the rules can be mixed or individual. Hope I helped you