I'm primarily using Postbox with Gmail IMAP (http://postbox-inc.com http://postbox-inc.com) - full featured and a bit nicer than Thunderbird. I loved Sparrow bu

I'm primarily using Postbox with Gmail IMAP (http://postbox-inc.com http://postbox-inc.com) - full featured and a bit nicer than Thunderbird. I loved Sparrow but found it wasn't powerful enough for multiple business accounts. Search could be a bit nicer as I tend to keep a gmail window open as I often need to reference older emails.