QuickerSite is available on GitHub as from 2020.
You may want to star, fork, follow, download and/or contribute to the project over there. Thank you!
SendGrid turns out to be a working solution for sending out emails in QuickerSite. The settings below (/asp/config/web_config.asp) work fine for me. You have to signup and create an API key. Finally, use the password for that API key. You can send up to 100 messages/day for free.