@matigo oi, this tells me I didn't explain this well enough. I get the emails in my email already. I'd just hit fwd, or set that up automatically to forward to a fixed email address.
I sorta want https://kill-the-newsletter.com but for newsletters I've already subscribed to. I know I should bite the bullet and just use the site instead, but I'm lazy AF.
As for why I'd rather do this in RSS - that's my reading space. Email is for work or focus. I ****hate**** when I get newsletters in my email.