PopTrayU - Have you fallen in love with the fabulous email notifier program Poptray, but you're running a...
Shift - Shift is the ultimate email client for managing Mail, Calendar, Drive, Slack, Asana, Jira, Evernote, and all your other favourite apps
Checker Plus for Gmail - Displays new emails and the sender's contact photo, get notifications or even listen, read or...
Mia for Gmail - A desktop email client for your Mac, without a browser !
Gmail Notifier (restartless) - is a highly customizable browser extension that notifies you about the incoming emails from all your Google-Mail accounts and labels. Gmail notifier is available for Firefox, Chrome, Opera and Safari.
Mailplane - Mailplane is the best way to use Gmail on your Mac. Use an unlimited number of accounts, get new mail notifications, use plug-ins and much much more.