How to delete a public key

A group member deinstalled delta chat and is now still receiving encrypted mails from DC group.
Is it possible to delete his former public key so he is again able to read the mails with normal e-mail client?

Hi, did he leave the group before uninstalling Delta Chat? I see more than one issue here:

  • He still is a member of the group. (Solution: Anyone who is a member of the group must dismiss him.)
  • He did not import his personal key - the one in Delta Chat - in his common mail client.

If possible, he should reinstall Delta Chat and restore a backup, because it includes his public and personal keys which he used. (This way, he could dismiss from the group by himself.)

However, he still could receive encrypted mails of 1:1 (personal) chats in a common mail client. If he decides not to use Delta Chat anymore, he could

  • disable preference for encryption, and send at least one message to the other Delta Chat clients (to let them know automatically), or
  • import his personal key (maybe together with his public one taken from an encrypted message of him) in his common mail client, so that he can continue to read those messages there. (I did a test with my Delta Chat keys and imported them in Mozilla Thunderbird, and it has worked well.)

Thank you for your suggestions.

I am using DC and the group to contact the members via email.
Some members tested DC and one decided not to use it anymore. He deinstalled the app and now he is still receiving my messages with e-mail but is not able to read the encrypted messages.
How can I config DC to send him decrypted emails again?
He wants no new email address and not to use encryption.

You can’t do this, but he can: He just has to send an unencrypted, normal email to everyone. Then your Delta Chat will realize that he can’t use encryption anymore and send unencrypted.