Hi HN,

I am building an email screening service for Gmail. Given that LLMs have more or less passed the Turing test and looking at the number of LLM-wrapper startups in the making, going forward, I doubt that humans and AI writing can be meaninguflly distinguished and email seems slated to become an even noisier communications tool.

Inspired by Hey.com’s feature, I am trying to build a service that screens first-time senders in a deterministic way (yes → all emails reach inbox; no → all emails go to trash).

My application needs to:

- receive webhooks when a new email is received

- move emails to trash, to inbox, or to archive (depending on whether it's blacklisted or whitelisted or neither)

- when a user sends an email, automatically whitelist the recipients so any replies won't be screened

Based on Gmail's policy, these operations require "sensitive scopes" and I will need to pay for a Tier 2 Cloud Application Security Assessment (CASA). To be fair to Google, most of the rules and requirements are pretty clear (create a YouTube video, illustrate the data flows etc.), but some key uncertainties remain:

1. Has anyone done this assessment before and is able to advise on the process? Specifically I am interested in:

- How much it costs or otherwise has a recommended company? (Please drop me an email at hello@inboxhero.org if you don't wish to disclose publicly.) Almost none of the companies doing the assessment publish their prices online and I am worried about getting ripped off.

- How does one write a privacy policy and/or a terms of service? I am working on this myself and don't have experience doing this. I have found some generators online, but am not sure which to use/trust!

2. From a security perspective, how does this assessment ensure that the application isn't misusing user data? I understand that I don't need to share my source code with the company doing the assessment (unlike my previous experience with pen-testing) and the assessment is done once every year (so who's to say what is happening with the data flows in the meantime). I am not sure if this is security theater.

3. In my test with early users (mostly friends and family), I am told that they are only willing to grant me the extensive permissions needed to screen emails because they know me personally. From a user perspective, what would it take for you to trust a stranger on the Internet? Is saying "I've verified with Google!!" is enough, or whether I should try other ways to build trust. Get the endorsement of influencers? Open source the code?

Would be grateful for any advice, both for the security assessment and for the product in general. Thanks!