Mailo - Mailo is an email client where you can send and receive emails to and from anyone with an email address.

Kiwi for Gmail - Dedicated Gmail client with clean integration of Google Calendar, Contacts, Google Drive, and...

HEY - Email at its best, new from Basecamp.

Shift - Shift is the ultimate email client for managing Mail, Calendar, Drive, Slack, Asana, Jira, Evernote, and all your other favourite apps

Horde - Horde Groupware is a free, enterprise ready, browser based collaboration suite.

Wavebox - The powerful productivity browser like no other, multi-account sign-in, tab sleeping, groups & pins