Can you please give a bit more detail about what you are trying to do. Is this regarding emails. Or are you trying to sync between different machines running firefox or firefox beta ?

As far as I am aware bookmarks for firefox are kept entirely on your own local machine. (Unless of course you opt for some deliberate method of web storage/backup - but that is not part of firefox)

I have just posted in another thread about firefox and restoring bookmarks from the auto backup bookmarks that may be of interest to you.

If you have accidentally removed bookmarks then use "Organize > Undo" in the bookmarks manager (Bookmarks > Organize Bookmarks) to get them back.
The Organize button is the first of the three buttons on the toolbar in the Library (Bookmarks Manager).
That only works if you haven't closed Firefox.
If it didn't work then you can restore the bookmarks from a JSON backup.
This will replace all current bookmarks and you lose bookmarks that were added since that backup was created.

See http://kb.mozillazine.org/Backing_up_and_restoring_bookmarks_-_Firefox

Thank you. I found the "restore" functionality under there. That's great. Thanks again.