I would like to mention another great tool: Clearout: Email validation and verification service. It is easy to use, GDPR compliant, affordable It has high accuracy and exciting features like bulk verification, lead finder tool, seamless API integration, compatible with Hubspot, Zapier, Google sheets, etc. check out the tool here: https://clearout.io/ .

Еще можно к этому списку добавить https://mailcheck.co/ ребята очень круто интегрировали верификация на базе соц сетей до 500 имейлов трайл, если не ошибаюсь.