The new spamsieve V3 works for outlook for mac without having to revert to old outlook?
You still need to uncheck New Outlook because New Outlook doesn’t support AppleScript yet.
Note that unchecking New Outlook will make you add all your accounts again, one by one. Personally I use Mail for work and personal email, while Outlook for Mac is only used for my Gmail accounts. Not a big issue, but noteworthy.