I also have authentic emails being marked as spam. This is applies to all emails I receive from mythic beasts or via their server.
The email source includes:
X-CNFS-Analysis: v=2.4 cv=bLzTnNyZ c=1... etc.
followed by X-Spam-Action: folder Spam
If I change the mailbox setting to “Flag a message as SPAM but deliver to Inbox” or “Turn off all SPAM filtering” then all kinds of rubbish goes into inbox, but the authentic emails from mythic beasts still go into spam.
I rang Virginmedia about this on 29th Jan, and was told an engineer would look into it that afternoon but it hasn't been fixed and I haven't received any feedback.