An email client that combines Gmail's web interface with a slew of additional features, including integration with OmniFocus.
MailPlane is touted as the “best way to use Gmail on your Mac”. It’s designed to give you the power and convenience of the web-based web client while also introducing features that can only be delivered through a dedicated app. For example, Mailplane integrates with the Contacts app and can be set to be your default mail application.
The app integrations that are built-in to MailPlane include a “Save to OmniFocus” feature. Selecting this command pops up the OmniFocus Quick Entry dialog with a new action matching the subject of the email. The notes field contains two links: one that allows you to return to the email from within MailPlane and a second that provides access to the email through the standard web interface. If there is any text selected, this text will automatically be added to the notes field of the new action. Otherwise the entire contents of the email is stored in the notes field.