Can't filter and forward all incoming mails to special account

Hello!

We are new to 365 and outlook and exchange. We are a small company with 20 accounts. All works well except one major thing. We want to filter every incoming mail by searching the subject for "##". Those incoming mails are likely to be responses to our own mails which we sent out already having ## in the subject. We want all those filtered messages to be sent to the recipients PLUS to a special inbox "filemaker(at)..:". Our Filemaker server checks that inbox and loads messages into our Filemaker database. That had worked perfectly in the past.

I know I am looking for a "mail flow rule" ... but all the existing selectable choices don't work. It seems like a very simple task though. Maybe someone has an idea?

Thanks

j.