github.com/maildev/maildev
maildev (SMTP mock server) を使ってハイパーメール開発
$ npm i -D maildev
$ npx maildev --ip localhost
> MailDev using directory /var/folders/2h/c616w1013n99fpgzz9gw7cx80000gn/T/maildev-16834
> MailDev webapp running at http://localhost:1080
> MailDev SMTP Server running at localhost:1025