Postbox is a beta Mac/Windows email client which I have been trying out. It is built on Mozilla Thunderbird by one of the original Thunderbird developers and it has a few nifty features which make it worth a look.

If you are a Gmail user you will be familiar with the concept of archiving old mail, Postbox allows you to do this and is integrated with Gmail’s archive function. It also groups inbox messages into conversations, which helps to keep everything organized, and only requires a username and password to get Gmail or Google Apps Mail running.