NeverBounce - Real-time email verification and cleaning to ensure emails never bounce.
Short - The reading list for busy people
Email List Verify - The Fastest Way to Improve Email List Deliverability and ROI
7reads - A minimal mindful reading list for Google Chrome.
ZeroBounce - Removes invalid emails from your list to prevent email bounces from ruining your deliverability.
Votum for Slack - Crowdsourced lists with upvotes, inside Slack