When I try to set my Junk E-mail filter to “No Automatic Filtering”,
Outlook will switch it automatically back to Low.
How can I completely turn off the spam-filter?
This happens when you have a Live Hotmail account configured in your mail profile.
Besides email, the Outlook Connector also syncs your Junk E-mail settings as you have them configured it in your web based Live Hotmail mailbox. However, the lowest possible setting for the Junk E-mail filter in the Live Hotmail web interface is “Low”. There is no way to turn it off completely in the web interface so you won’t be able to turn it off completely in Outlook anymore either as the “Low” settings would sync back.
A solution would be to use POP3 to connect to your Live Hotmail mailbox instead. Currently POP3 access isn’t supported for all Live Hotmail mailboxes worldwide yet, but will follow soon. For an overview of the settings that you’ll need in order to configure POP3 access to your Live Hotmail mailbox see this guide.