Mailplane is a Gmail desktop client designed for Mac users who wish to easily manage their Google mail account. This program comes as an alternative to using your default web browser for handling your Gmail account. It helps you quickly check your Inbox, send emails, chat with other Gmail users, etc.
The utility features a straightforward interface, supports drag-and-drop actions, and lets you define various shortcut keys for immediately completing tasks (start a new message, toggle "Do Not Disturb" feature, etc.).
Another great advantage is the fact that you can use this program to manage multiple Gmail accounts. Enter the credentials for your Gmail accounts in the Preferences panel of the tool. Then, Mailplane will assign one tab per Gmail account and you can switch between the tabs whenever you need.
The tool also puts a small menu in your status bar that shows you a list with the latest emails you received in your Inbox and provides you with a quick way to start composing a new email.
To sum things up, Mailplane is the best Gmail desktop client I tested on my Mac. It's filled with numerous helpful features, works perfectly without slowing down other running programs, and is affordable. It's definitely worth a shot.