Reading mork files

Mork is a somewhat mysterious database format used by Firefox and Thunderbird. Even if it's pure text it's impossible to 'read' the file. See wikipedia.

There are few sources of information about mork in the web, mainly:

Primer
Grammer (V1.1, current is 1.4)
Structure
Sourcecode

mork was and is used by:

Firefox
- History file (history.dat, obsolete)
Thunderbird
- Addressbooks (*.mab, obsolete, up to TB68)
- Mailbox summary files (.msf, still in use!)
- Mail folder cache (panacea.dat, obsolete, up to TB91?)

and probably more i'm not aware of.

I've tried to find some programms which are able to read mork files. I found some python scripts, which i didn't get running and a perl script that was able to read the Firefox history files but not the others. With the help of the sources mentioned above and some reverse engineering i've managed to extend this perl script to read all the files, to some extend.

Since perl is not very widely used, I rewrote the parser in php.

mork.pl (2.2.2025)

mork.php (2.2.2025)

Reading mork files with thunderbird (3/28/2025)

Since Thunderbird daily 138.0a1 (2025-03-28) it's possible to read mork files with Thunderbird!
See the announcement in the topicbox.

Open Thunderbird with the '-console' commandline parameter. Open the properties of a folder and click (or shift/click) on the text 'Sometimes the folder index (.msf) file becomes damaged ...'. Now the (native, not the error-) console contains the content of the mork file in json format.
Since it's difficult to extract the output from the native console, there is another way:
Open Thunderbird with the name of a .msf file as a parameter and redirect output to a file:
thunderbird file.msf > file.json

To read ancient .mab addressbook files or other mork files, rename them to .msf and use the second method above.

28. März 2025, G.Gersdorf