I downloaded the app and tried to sign up, but it said "Invalid request data!" after I submitted the form.

Is it supposed to work ATM?

What are your thoughts on code intelligence (intellisense) in a coding interview tool?

There is a new standard called Authenticated Received Chain (ARC) designed specifically to address the DMARC authentication failure issue caused by mailing lists. Basically what ARC does is to preserve SPF/DKIM authentication results, and use them to override DMARC authentication result when deemed appropriate. There is a Quora post here for a more detailed explanation: https://www.quora.com/What-is-Authenticated-Received-Chain-A....