Gmail Add-ons - Work with your favorite business apps directly in Gmail
Shift - Shift is the ultimate email client for managing Mail, Calendar, Drive, Slack, Asana, Jira, Evernote, and all your other favourite apps
Brevo - Innovative online Email Marketing solution to manage your contacts, create & send your newsletters and track your results. More than 80 000 clients. Best prices and attractive features.
Mia for Gmail - A desktop email client for your Mac, without a browser !
Shortwave - Email smarter & faster with a reinvented experience for your Gmail
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.