1 - First, we cross reference IP addresses we assign to gateway against known blacklists. This helps ensure emails will be delivered. We also fully support email authentication (DMARC, DKIM, SPF) and configure reverse DNS as well. Lastly, the IP address for a gateway stays fixed so the domain and IP will build reputation over time. Helm servers require the service to work to get around the residential internet connection challenges in the US (port blocking, dynamic IPs, untrusted IPs)
2 - We will be doing 2 things - first, we will publish as open source what is required for people to be able to run their own gateways with their own AWS account in the event Helm has to shut down. Second, the unit economics on the service are positive so as long as we have customers, my co-founder and I are dedicated to running the service. We take a page from Garry Tan and Posthaven in this regard.
3 - The way this works for sending emails, your devices that you compose emails on will connect directly with your Helm server over TLS. Your Helm server will then initiate a TLS session with the server hosting your recipient's email. So we as a company have no visibility to any of that data - at rest, or in transit. I hope this helps - I'm happy to explain this in more detail as needed.