Verifier - Weed out disposable, non-existent domains or invalid emails.
Spark Mail - Spark helps you take your inbox under control. Instantly see what’s important and quickly clean up the rest. Spark for Teams allows you to create, discuss, and share email with your colleagues
Email Verification on Google Sheets - An add-on for email verification directly in Google Sheets
Polymail - Native email app for email productivity.
Email List Verify - The Fastest Way to Improve Email List Deliverability and ROI
Clean Email - Clean Email is an online service that empowers you to take control of your mailbox.