Thunderbird works well for me. Interfaces with GMail IMAP. Has a nice quick filter and all the usuals (filtering, folders, labels). The calendar interfaces wit

Thunderbird works well for me. Interfaces with GMail IMAP. Has a nice quick filter and all the usuals (filtering, folders, labels). The calendar interfaces with your Google calendar too (with the Lightning and Provider for Google Calendar add-ons). Available for Mac, Windows and Linux.