Sparrow is a minimalist mail application for Mac. It was designed to keep things simple and efficient. No fancy stuff here... just your mail and nothing else.

Threads - Quickly flick through threaded conversations on your Mac like never before.

Not so minimal - See your mails the way you want. Quickly glance at the preview. Read it in a new window or open the right pane to enjoy Sparrow's full potential.

Notifications - Growl is integrated for notifications addicts.

Multiple Accounts - Seamlessly switch between your mail accounts.

What's next? - Sparrow will soon support several IMAP email providers and integrate labels for Gmail users.

WHAT'S NEW
Version 1.6.2:

New Features:

OS X 10.8 Mountain Lion and Notification Center support
Retina Display support
Send & Archive in Quick reply
Always expand messages option
Always show the 'i' section
fixed close/minimize/zoom button behavior
enabling always show info will show info of the opened messages
enabling always expand all will expand all messages


Bug Fixes:

Growl Notification with Growl 1.3
Growl Notification for POP accounts
Memory consumption improvement
Requirements
Intel, Mac OS X 10.6 or later 

If you like it - buy it