GMass - GMass allows you to easily schedule emails, send out mass emails and mail merge campaigns and more with Gmail! Click here to learn about more features!
SyncWith for Google Sheets - Data from any app into Google Sheets, reports & dashboards
Trumail - Free email verification API
SheetHacks by Polymer Search - Discover the best tips & tricks for Google Sheets & Excel
ZeroBounce - Removes invalid emails from your list to prevent email bounces from ruining your deliverability.
Sheety - Turn any Google sheet into an API instantly, for free. Power websites, apps, or whatever you like, all from a spreadsheet. Changes to your spreadsheet update your API in realtime. Neat