PostBox is a new email client for Windows and Mac with a rich set of features that makes it stand apart from existing email clients. PostBox borrows it’s looks as well as the code from open source Thunderbird, and then adds a slew features on top. The most notable improvements of PostBox over thunderbird are faster search, better message organization, message tagging and integration with online services.
PostBox’s powerful search features enables you to quickly search your messages using various search operators such as "from" or "subject". Postbox is even said to understands search terms such as after "last Monday" or before "June 2008."
PostBox uses tabs to open messages just like web browsers do, and you will all agree that tabs are the best way to manage multiple open windows. You can open almost anything in a tab, including messages, folders, searches, or content such as attachments and images. Click on the attachment tab to quickly view all attached files or view all images in the image tab.
Another useful feature in PostBox is the conversation view that enables you to view and process messages by conversation. Simply select a summary row in your message list to see a roll-up of all messages within a conversation.
For organizing messages, you can use the traditional approach of using folders to sort messages or just assign tags to them. Using tags is advantageous as you can assign multiple tags to the same message.
Do you love Gmail’s Archive feature? PostBox has one too. Just click on the archive button to move messages into a dedicated Archive folder. You’ll still be able to find those messages using it’s powerful search features.
Postbox can also integrate your email content to the various online services. You can upload images to Picasa or documents to Google Docs without leaving the email client. Select any text from a message and post it on Twitter, Facebook or Friendfeed or make a simple search on Google, Wikipedia and such.
PostBox supports both POP3 and IMAP, and automatically configures email account of popular service providers like Gmail, Windows Live, Yahoo and AOL. It also functions as a basic RSS reader.
Update: Postbox now supports addon