Does the job!
TLOxp - TLOXP
NeverBounce - Real-time email verification and cleaning to ensure emails never bounce.
Lampyre - Lampyre - an efficient data analysis and OSINT multi-tool for everyone.
Email Verifier - Email verifier app lets you verify email.
Netglub - Netglub, the really open source information gathering solution.
Email List Verify - The Fastest Way to Improve Email List Deliverability and ROI