Thanks a lot for the in-depth, enlightening answers. I’ll mark this answer as solution.
Let me add some comments, though.
best is if average user do not even think about if they need an email account or not. install the app - choose a name, done
I agree, that for average users ChatMail makes onboarding much simpler (as there is no fiddeling with email accounts). And this aspect should not at all be underestimated! This is what is expected for a chat application for many users nowadays. However, see the comments on the disadvantages of that approach below.
Compatibility with non-DeltaChat e-mail users? … not easy
IMHO, this is quite a thing. Doesn’t ChatMail put DelaChat users into a bubble like Matrix and also WhatsApp do? Hm! And BTW: No average user will even understand the consequences of the default choice (ChatMail as default over email accounts).
if you do not switch on your device in that three weeks, yes, you will miss messages when using chatmail
Thanks for explaining the reasons. Personally, I fully understand and support GDPR. However, people should know about that when chosing ChatMail.
Can I keep/move a ChatMail account to another host? … not yet
Okay, very important to know. Personally I find this quite critical. I cannot really recommend ChatMail then until this feature has been added as it is unclear whether this feature will be implemented at all and whether there will be a smooth transition.
Thanks!