Shift

Having to work with multiple email services in tandem can be a bit confusing and quite counterproductive. Considering that feature-packed email services, like the popular Gmail, also provide you with calendar features and cloud-based sharing possibilities, things can quickly become downright annoying.
Shift is a modern-looking and efficient, cross-platform piece of software that allows you to instantly toggle between multiple Gmail accounts and all their annex services like Google Calendar and Google Drive within a single roof.

Intuitive email app that can be effortlessly deployed on all the key OSes

The app works on all major OSes out there, namely Windows, macOS and Linux and also comes with support for Outlook and Inbox.
It can be deployed on your computer in practically no time and with the minimum amount of fret, thanks to a typical, streamlined installer. As expected, once you launch the utility for the first time, you are required to connect to at least one account.

Novice-accessible UI and workflow

Simply input the email address, choose a name and a color that are best representative and, at the next step, add the password and that's that. You should be able to easily find your way around this app since you should be Shift boasts an intuitive, gray-themed, and stylish user interface.
Navigating between your accounts requires but a few mouse clicks on the left-sided toolbar, while extra functions such as the Google Calendar and Google Drive can be accessed from the top toolbar, on the upper right side of the main window.

Customize your experience with the app from its streamlined Settings menu

You can be sure that you will not miss any important emails with Shift since it also comes with support for native desktop notifications. Since we are on the subject, we should also note that the application is quite customizable.
For instance, from the General section (within the Settings menu), you can tweak the utility to your exact needs by enabling or disabling the badges, the app's tray icon, the spell-checker, and the sounds.

Work with multiple email accounts in a clutter-free environment

All in all, Shift proved itself to be a very handy and versatile application that is clearly intended for users that are fed up with having to deal with multiple email accounts using their computer's browser.
The application is easy to install, has a modern and intuitive interface, comes with support for some of the most popular email services, smoothly-integrates with your computer's system, and it is fairly customizable, all this without hogging your computer's resources.