Email Checker offer a batch API that you can easily integrate, which will allow you to automate the sending and retrieving of files for verification.
You can sign up for a free account and test the solution here: login.emailchecker.com
Also if you enter CHECKER10 at checkout, you will get 10% discount off your order.
MailboxValidator has API plans which you can use easily.
We also have ready made integrations if you are using some of the major email service providers like MailChimp, etc.