You can enable the email verification extension from Backend > Extend > Extensions, and from here, you can enable one of the available email verification providers. After you do this, login as a customer, and on the left side menu, you will see the email verification menu, where you will be able to insert the api key for that given service and also select where verification happens, you can select to verify emails as you import them. Then, you can go to your email list and simply import your emails, and it will actually verify them with your email verifier of choice.
Or you can as well verify those emails with your email verifier of choice, then import them in MailWizz, when you know they are good.
For 33 emails, I'd really use the second option, it's just faster.