Today I mentioned a post at ApfelWiki (german) and decided to test it with RSS Bandit's Remote Storage feature (used to sync. your feedlist/flagged items/search folders with other machines running RSS Bandit). It just works and also supports https: to keep your password a secret. Here is how to setup if you already a member/user of the free services at GMX:

1. Open Tools-Options dialog
2. Select the "Remote Storage" tab
3. Check the "Use remote storage" checkbox
4. Select "WebDAV" from the Protocol dropdown
5. Type https://mediacenter.gmx.net/ within the WebDAV folder url input box (important: it is gmx.net, not gmx.de!)
6. Provide your user name and password you use to login at gmx: e.g. <your account>@gmx.de
7. Press OK

[thanks to schockwellenreiter.de]