As a user it’s not clear to me what would happen in the scenario that Alice and Bob are introduced to each other by a mutual contact, Bob’s fingerprint changes, and the mutual contact verifies Bob’s new fingerprint — would Alice be notified about the fingerprint change or not?
It has also been pointed out by others elsewhere that the wording used by Delta Chat when a fingerprint changes (e.g. “setup changed” or something like that) might be too vague for users to understand the implications.
I think there is some mixed truth to this. As @Raiden says “everyone is likely to have at least one email account” and in my experience, 100% of people I’ve asked have an email address, even if they don’t use it as their primary communication channel. Unfortunately, some emails, including from the “privacy-focused” providers Proton and Tuta, don’t let you use IMAP with a free account, which disqualifies them from Delta Chat.
As you point out, in many situations it feels more natural or normal to ask for a phone number or an Instagram than an email address, but that’s really just a matter of social convention and stigma, and we can help to change that.
Also depending on where you live in the world, your economic situation, etc, phone numbers might be much less accessible than email addresses, and we shouldn’t assume that just because a certain type of demographic tends to use phone numbers more often than email, that this is true for everyone. If we all go along with the narrative pushed by apps like Signal that “we live in a phone-first world”, we might just end up inadvertently creating a world like this!
Ideally he would separate “tracker” and “telemetry” into different categories, but many less scrupulous apps (and operating systems) use “telemetry” as a euphemism for “trackers”, so this could get quite confusing and it’s not always clear where you draw the line, as data used for statistics can sometimes also be used for tracking.
I agree that chatmail is a big improvement. The flexibility which chatmail provides, the ability to easily sign up for a chat-optimized account or even multiple accounts without needing to provide personal details is a game changer. But the experience would be much smoother if the UI included something like a “generate chatmail address” or “sign up with chatmail” option. Firstly this would help people who use the Tor Browser, which doesn’t allow the chatmail webpage to open the Delta Chat app. Secondly, it would help to onboard new users and solve the “Hold up, where is the “Sign Up” button?” issue described by @WofWca.
I look forward to seeing how chatmail evolves in the future!
The multi-account capability is definitely an advantage, but still the fact that you access all your accounts at the same time and from the same IP address means that if your accounts are hosted on the same server, the server could associate your different accounts. To reduce this risk, Delta Chat would need to stop automatically checking all accounts simultaneously (currently an experimental feature for desktop only) and use Tor circuit isolation for each of your accounts.