There are a gaggle of services available that will validate emails for customer lists. They provide a way to filter out invalid emails and handle other issues.
One of them is Zerobounce
They have an interactive email verifier: www.zerobounce.net/free-email-verifier.html
An API is also available, 100 free per month if you just want to test it out.
One of them is Zerobounce
They have an interactive email verifier: www.zerobounce.net/free-email-verifier.html
An API is also available, 100 free per month if you just want to test it out.