What most backup software do is to make the backup of all emails so that they can be restored in case of any disaster or can be restored to another computer if you are migrating. But have you considered a case where you need to make a backup of your emails in such a way that you can read them using any popular web browser.
Mozilla Thunderbird uses Mbox format to save all emails. Mbox2Xml is a free tool for Thunderbird that has the ability to extract emails from Mbox format and convert them to Xml format. It even converts the attachment directories and adds them with Xml spreadsheet so that you can access the attached files too.
Here is how it works, first give the backup a name, choose the Mbox files that you want to convert, select the output directory, choose the Start/End Date and Time of the emails(all emails between these dates will be converted), and finally choose some additional options. When all is done, hit Convert.
If you don’t know where Mbox files are located, there is a build-in option to scan the directory for Mbox files.
Note that many other email clients also support Mbox format so this tool can be used to convent them as well. Xml format is widely supported, so it can be easily imported to most other programs.
It works on Windows XP, Windows Vista, and Windows 7. Enjoy!