Email Verifier - Email verifier app lets you verify email.
Lotame - Make your data actionable, learn about your most valuable customers, improve ROI by targeting the right audience and increase relevance across screens.
NeverBounce - Real-time email verification and cleaning to ensure emails never bounce.
Adobe Audience Manager - Adobe Audience Manager is a data management platform that integrates online and offline data to deliver a unified view of all your audiences
Email List Verify - The Fastest Way to Improve Email List Deliverability and ROI
Google Audience Center - 3 votes and 6 comments so far on Reddit