To throw another hat into the ring, I liked "Designing Visual Interfaces" by Mullet and Sano. It has one of my favorite quotes:
> Without minimizing the value of intuition as a problem solving tool, we propose that systematic design programs are more valuable from a communication standpoint than ad hoc solutions; that intention is preferable to accident; that principled rationale provides a compelling basis for design decisions than personal creative impulse.
Relay is a good service, but if you're interested in one with more features I'd recommended SimpleLogin: https://simplelogin.io/.
The biggest addition for me is SimpleLogin's log of where the emails were forwarded from, and being able to associate aliases with different emails. With Relay I have to go digging around in my email trash or password manager.
> Without minimizing the value of intuition as a problem solving tool, we propose that systematic design programs are more valuable from a communication standpoint than ad hoc solutions; that intention is preferable to accident; that principled rationale provides a compelling basis for design decisions than personal creative impulse.