email address validator - Robuta Search

https://wordpress.org/support/plugin/email-address-validator/reviews/?filter=3

https://verify-email.app/

Check if an email address or domain is deliverable, disposable, or privacy. Protect your product from abuse and clean email list.

https://mailinput.com/

Check if an email is valid with our free online email verifier. Send your emails with complete confidence. Never get bounces anymore.