- Download the EmailBackup.zip package. Do not unzip it.
- Choose Tools -> Extension Manager.
- Select My Extensions and press the Add button.
- Select the EmailBackup.zip package and press Open.
If you want to know more about how the extension works, take a look at the OOoBasic crash course: One-click email backup of OpenOffice.org documents article by yours truly.
Download: Email Backup Extension
The Email Backup extension is released under GPL.