Maybe. EncryptionResult has a list of invalid recipients and I've changed the code to show the Retry dialog only if there's at least one invalid recipient.

Your suggestion sounds ok to me, maybe with a slight change for the message: "Failed to encrypt the notepad because at least on certificate could not be validated."

I tried to add the list of invalid recipients to the message box, but it seems that gpgsm stops the validation of the certificates at the first invalid recipient. I got only the first Bob certificate reported as invalid recipient when I tried to encrypt to both Bob certificates so that it doesn't make sense to list the (incomplete) list of invalid recipients. It also means that Kleopatra cannot update the invalid recipient certificates because it knows only of one invalid certificate.

Ideally the certificate would change, but Kleopatra has no idea that this certificate turned out to be not valid. In fact, Kleopatra doesn't even know that the encryption failed because of some certificate. It could have failed for any other reason (e.g. full disk). Kleopatra only knows that an error occurred and offers to retry with lower security. (I looked at GpgOL and it does the same.)

yes, basically it's what we want.

Current implementation for the case of an S/MIME certificate which turns out to be invalid when it's used for encryption. Is that what we want?