is there any way to respond to an incoming email that’s not sent via DC?
Hello 
,
so far it is only possible to reply to encrypted emails. This is intended to prevent spammers from abusing the chatmail server.
More seriously, Delta Chat uses the decentralized Autocrypt standard which does not publish or centralize encryption keys anywhere. Moreover, today’s Internet platforms track everything except OpenPGP keys and so can only sell or leak to spammers profiled e-mail addresses but not encryption keys. It’s therefore a massive uphill struggle and economically un-interesting to abuse chatmail accounts for mass-sending unsolicited mail.
got that, but if the email was incoming 1st, I’m no spammer responding to it. Except I can fake this incoming mail, ofc.
Well actually you can’t fake incoming mails to chatmail server as it rejects all mails without a valid DKIM signature.
well, then it only would be fair to be able to respond to incoming mails, unencrypted.
chatmail setups could allow mailing back unencrypted if a mail was previously sent from the target address. This was in fact the original idea for implementing an open-signup chatmail service but
this “hole-punching” scheme does not work well with groups: If you get added to a group you can mail back to the group creator but not to those members who haven’t sent you a mail. Usability-wise this might be pretty tricky/unexpected.
The other impediment for is how much chatmail should process unencrypted e-mail at all. From an operator standpoint it’s better to only have encrypted messages (even enforced for incoming ones, and intra-chatmail service ones) because then there is hardly any data that could leak in case of hackings or court orders.
I would amend the FAQ with it explicitly, it took me some time to understand that it’s (responding) not working (although it’s mentioned that unencrypted emails are not supported)