Sending E-Mails to multiple recipients based on postal code the user types in

I'm building a website with Wordpress and currently the Ninja Forms plugin. My problem is the following: I would like to send e-mails to recipients in the vicinity of the entered postcode based on the entry of the postcode field. With the Ninja Forms plugin, it is only possible to assign different addresses to each individual zip code. However, this would be too much effort and if new addresses are added, it would be impossible to monitor.

I have a CSV file with the address and contact details of the recipients. Is there a way to achieve this, regardless of the tools (it doesn't have to be Ninja Forms)? But it should run on a PHP based website (with Wordpress).

Thanks for all the tips.