Ask HN: Tool for ad-hoc collection of answers from clients?

I have a wonderful client at the moment that I'm enjoying working with -- but in my 20 years of freelance work, I've never had such communication issues.

I try making it easy by asking questions one by one in a numbered list and keeping it to no more than 5 questions per email, but inevitably, I never get all of them answered.

This is taking a huge toll on my time just trying to wrangle getting answers to simple things I need in order to complete my work.

I think email is just not working for this client, and I believe there must be a better way.

I'm wondering if there is something with a user flow not unlike survey sites such as SurveyMonkey but is specifically targeting to ad-hoc answering. My client may not have all the answers available at a given time, so I want them to be able to revisit the page and edit previous answers and provide answers to questions they have not answered yet.

The important thing is that I believe just having a wall-of-text list of questions is what is not working for my client, so a more expanded workflow with a tally of # of questions answered vs not answered would be ideal.

I've also tried just asking one question per email -- does not work either.

Is there an existing tool that the HN community uses?