Does the job!
NeverBounce - Real-time email verification and cleaning to ensure emails never bounce.
TheChecker.co - Accurate email verification at low prices.
Email Verifier - Email verifier app lets you verify email.
Email List Verify - The Fastest Way to Improve Email List Deliverability and ROI
TrueMail.io - TrueMail.io is an email checker service.
ZeroBounce - Removes invalid emails from your list to prevent email bounces from ruining your deliverability.