I think I'm missing something but I've have an option to use <anything>@<ident>.domain.com for couple years now.

I don't find it that useful though and usually go with standard alias i.e. user+<anything>@domain.com

As for single sender locking - not sure how useful that is. I mean you can get github.com email or notifications.github.com so you miss half of them?

On the "+" sign comment: I find that many spammers already know the trick. That's why I built a prefix where any suffix will work. If you have "turtle" as a prefix, you can add "turtle$bank", "turtle-barber", etc on the spot, without having to create each suffix.

As for single sender, we attach to the domain, so *.github.com would be allowed. The main problem, to be honest, is when email comes from apple.com, icloud.com, applehq.com, etc. I'm considering a power-feature where you could pre-select a few domains or allow all and then lock it. I feel it would be best for power users only. What do you think?