Postbox is een e-mailclient die zijn oorsprong kent in Mozilla's Thunderbird. De ontwikkelaars hebben daar tal van mogelijkheden en verbeteringen aan toegevoegd, en het is mogelijk om de functionaliteit met extensies verder uit te breiden. Hierbij moet worden vermeld dat de add-ons voor Thunderbird niet zonder aanpassingen kunnen worden gebruikt. Postbox ondersteunt pop3, imap en smtp op zowel Mac OS X als Windows XP, Vista en 7. De ontwikkelaars hebben versie 2.5 uitgebracht, voorzien van de volgende lijst met veranderingen:
Postbox 2.5 Update
- Improved Vertical view
- Improved compose window
- Inline quick reply
- Enhanced font size controls
- Improved message view
- Improved unread indicators in folder and focus pane
- Added support for playing a sound on send. Go to Preferences | Compose | Advanced to enable sound on send.
- Added support for Redirect via the Message menu and toolbar button (you must add the toolbar button through the Customize Toolbar function).
- Support for color and monochrome icons on Mac OS X (customize the toolbar to select a color or monochrome set).
- Added a toolbar icon to open and close the Inspector.
- Use Spotlight search to find messages by Topic keywords
- Added a remove text formatting button to the HTML format bar in compose.
- Lots of pixel pushing to make Postbox look awesome!
- IMAP support for Yahoo! Mail
- Improved migration and account setup wizard on Mac OS X.
- Improve UI for add-ons manager, account setup wizards for RSS and Newsgroups on Mac OS X.
- Replaced the Status Bar with an inline notification pop-up panel.
- Improved progress when loading messages
- New inline junk mail notification bar.
- Moved Search Options Panel button to within the Search Bar on Mac OS X.
- Attachment size should be visible in compose window
- Simplified "Insert Link" dialog in message compose
- Fixed an issue with twitter authentication
- Support CC and BCC and multiple attachments in AppleScript
- Bolding of unread messages in vertical view now configurable via a hidden preference.
- Performance improvements
- Stability improvements