This was attempted using the base-chain and a centralized forwarding service a long time ago. The company had the number 21 in the name. Tip-of-my-tongue.

Edit: This is also a centralized forwarding service. D'Oh!

You’re thinking of which was rebranded to

Yes and this is just custom Strike replacement for lightning address.

It does not solve spam problem. Emails leak by design and could be collected and used by third parties.