Windows

Postbox is now compatible with Mozilla dictionaries. 

• Download and save the dictionary to your hard drive. (Firefox users, be sure to right-click the download link, then select "Save Link As..." from the contextual menu.)
• In Postbox, go to Tools | Add-ons.
• Click the Install button and select the file you downloaded and click "OK".
• Restart Postbox and then go to Preferences (Tools | Options on Windows) / Composition / Spelling and select your default dictionary.

Mac OS X

Starting in Postbox 2.1.2, Postbox uses the system dictionary service and all of the dictionaries installed on your OS X system. To change the dictionary, go to Preferences | Composition | Spelling and select your desired default dictionary. You can also change this from the Spell check toolbar button in the compose window.

For information about installing on Apple dictionaries, see: http://support.postbox-inc.com/entries/427320-dictionaries-in-other...