I have successfully imported my existing PGP key into Delta Chat, but now I am unable to export a private key generated by Delta Chat for use with K-9 Mail, although that email client is Autocrypt capable.
So I sent the Autocrypt Setup Message from Delta Chat and opened that email in K-9 Mail, which by itself did not do anything. Clicking on the shown email attachment named
autocrypt-setup-message.html led to an error message (“Decrypt - Encountered an error reading input data!”).
I also tried with exporting the private key from Delta Chat, imported it in OpenKeychain (which is what K-9 Mail is utilizing), could see and check it there, but after that K-9 Mail was not able to recognize it as key for the used email address.
Is it possible that the key generated by Delta Chat is not usable by an (Autocrypt enabled) email application like K-9 Mail?
What else could the problem be?