We do not recommend using free domains. Since these domains usually have a bad reputation and usually poor service. Fake Email works with any domains and you can use it as you wish. If you intend to register a domain and in the future to be sure that you will not lose access to it, we advise you to use ICANN-Accredited Registrars.
Always keep in mind that using free domains you can always potentially lose access to it and someone can steal it from you.