Manage multiple Gmail accounts with Checker Plus - CNET
Gmail Checker - Multi Account Gmail Notifier
How to Check Which Apps Have Access to Your Gmail and How to Remove Them | Gadgets 360
Gmail Checker Lite (multi-account)
GitHub - nobuhito/atom-gmail-checker: Displays the number of unread messages in your Google Mail inbox. You can also click the number to open your inbox.
Verify email address whether it is fake or not
Free Email Checker - Verify email address without sending email
Manage multiple Gmail accounts with Checker Plus - CNET
4 Ways to Check Email by Using Google Mail - wikiHow