This is a client suggestion that has been implemented and appears in the Outlook Plugin settings. A menu option to open your Flex Site from Outlook is available under the SharePoint Flex icon in the toolbar:
When the “Open Flex Site” button is selected, a new browser window will launch, opening Flex site. The SharePoint address of the site is pulled from the ‘Credentials’ tab in the Outlook Plugin Settings.
Note: There is no action to take to enable this option.