Polymail - Native email app for email productivity.
Cardhop - The Mac contacts app you'll want to use.
Airmail - Airmail is a lightweight and lightning fast mail client for Mac.
Google Contacts - Google Contacts is Google's contact management tool that is available in its free email service Gmail, as a standalone service, and as a part of Google's business-oriented suite of web apps Google Apps.
Morning Mail - A new way to manage your mail. Tinder for email.
Keep In touch - Keep in touch with thousands of people