I use GMail (jumped on board the free GSuite back when they made it available and I was seriously done with running my own email server) as an IMAP service behind Outlook and Postbox. I’ve had my own domains for a couple of decades so no need to change email address. BTW, if you’re looking to do that, IMO the best place to get/keep/control a domain is namecheap.

GMail has a decent filtering capability, and it looks as though GScript (a lot like JavaScript), on top of that filtering, could do a lot of what this service does.

I use GMail filtering a lot, and GScript to delete anything past a set expiration date in the filtered-to folders — the whole bit is pretty clunky, but it does what I need and is a price I like (free). I’ve read that Google does not grovel the email of GSuite accounts, but I still encrypt anything private.