Mailbird is a great minimalistic Gmail client that has an intuitive and very minimalistic user interface, known from Sparrow - an e-mail client addressed to OS X systems users. To start working with this application you only have to provide it with your name and user password, and the program will configure your connection automatically. You don't have to manually set up your POP3, SMTP and IMAP configuration. Apart from options regarding managing your e-mail inbox, this application provides you with a couple of plugins that allow to improve the program's features, as well as access services such as Dropbox and Google Driver. Another interesting feature of this program is its available integration with your Facebook account.
To use the program freely you have to register on the producer's site and give your Gmail e-mail address that you will use with this application. A message with a password will be sent to your inbox and with this password you can log into Mailbird.