I use a free Gmail account as my mail client and direct all my custom domains from Fastmail to Gmail. Messages are delivered very quickly and I don't have spam

I use a free Gmail account as my mail client and direct all my custom domains from Fastmail to Gmail. Messages are delivered very quickly and I don't have spam issues. Truth is I like Gmail but I think Google have dropped the ball with, "Let me point all my custom domains to a Gmail account. I would even pay you but I don't want Workspace".