As a daily user of MsgFiler (because Apple still makes it incredibly awkward to file messages in specific folders after you’ve read them), this is a bit worrying, since it will stop working under Sonoma1 and thus completely break my personal workflow.
Hopefully there will be some sort of workaround do achieve what I’m used to, especially the quick, effortless fuzzy search for the destination folder–and no, neither filters nor the increasingly broken AppleScript support in Mail can replace this.
Ironically, Outlook for Mac has a similar feature, but I really don’t want to use it for my personal e-mail.
Update: Some people asked me “why not use rules”. That’s simple enough–there is no way to run rules after a message is read in your inbox. And since disabling the “Active” checkbox in Settings prevents them from running when you hit Option+Command+L in the message list, I can’t really use pre-defined rules to file messages on demand (if the rule is active, the messages will be filed before I can read them). If Apple allowed specific rules to be run with a hotkey, this would not be an issue.