I also recently upgraded to NIS 2010 and am running Outlook Express 6--the anti-spam icon only appears some of the time in the toolbar. It appears upon initial start up, then disappears after sending/receiving new email. The folder is still present, however--just the icon is missing. I clicked on the properties for the toolbar to customize it and the icon/file isn't even listed as an option to add. Additionally, I received a pop-up error message from OE (the gray box that appears in the middle of the screen) stating that there was a 'serious error' with the anti-spam plug-in and did I want to disable it. I clicked 'no'. I have had several problems downloading/receiving new email since upgrading to NIS 2010--i.e., a failure to execute the download. I have to run several attempts before I can get my mail. This was not occurring prior to the upgrade. It appears there is some compatibility issue(s) with Outlook Express and NIS 2010.
<<Edit: Edited message to reflect the changes as a result of moving the post to a thread of its own. Subject edited for clarity>>