ZeroBounce - Removes invalid emails from your list to prevent email bounces from ruining your deliverability.
Bulk Email Checker - Bulk Email Checker is an online service used to Verify and Clean Email Addresses. Its Easy to Use, Reliable and used by 1000's of Businesses.
NeverBounce - Real-time email verification and cleaning to ensure emails never bounce.
clearout.io - Clearout Email Finder & Email Verification Service - Drive sustainable business growth by expanding your reach, lowering hard bounces, and improving deliverability rates.
Email List Verify - The Fastest Way to Improve Email List Deliverability and ROI
Verifalia - Verifalia is a web-based email validation that lets users to upload and validate lists of email addresses.