Verifier - Weed out disposable, non-existent domains or invalid emails.
Grist - Grist makes it easy to transform spreadsheets into a custom database where data is truly actionable.
Email Verification on Google Sheets - An add-on for email verification directly in Google Sheets
Rows - The spreadsheet where teams work faster
Email List Verify - The Fastest Way to Improve Email List Deliverability and ROI
UProc for Sheets - Boost your sales, marketing and IT tasks from Google Sheets