Sounds awesome! I'm pretty happy with Thunderbird as is, but a modern interface potentially means more users... and hopefully as a result, a longer life.
Those survey questions are completely irrelevant to interface design. I use TB every day as my main private mail client and the picture they show me doesn't even look like what I use. Then they ask a bunch of marketing BS questions that have absolutely nothing to do with usability.
I hope these people stay the hell away from my favorite mail client.
I have to agree that the questions could have been better. For instance, they asked "Does this interface look trustworthy". What does that even mean?
I believe it's trustworthy because it's open source and backed by Mozilla. The only aspect of the interface that would lead me not to trust it is advertisements.
That being said, with good luck they'll get more useful feedback to the open-ended questions.
Here's a quick link to the survey: https://thunderbird-design.typeform.com/to/f7wiiq?utm_referr...