How send encrypted email only

how do i send encrypted email?
version 5.600 & 5.733 says:
encryption not possible. some of the selected receiptients dont support this feature

Get them to use clients that support it then I guess - you or your K-9 can’t change it if they can’t receive encrypted emails.

do you mean k9 will determine recipient supports encryption as soon as i type senders email id?

K9 probably “knows” which providers support it, I don’t know.

No, K-9 only relies on the information passed back by OpenKeychain.

If not all recipients have a public key in your database, you cannot send them an encrypted email. Thus, K-9 correctly tells you, that the mail cannot be encrypted as at least on recipient does not have a key.

In fact, an encrypted mail with multiple recipients grows linearly with the amount of recipients as the message is encrypted separately for each recipient and then combined into one GnuPG block.

1 Like

Is this a bug Or a feature

Best regards

It is good security practice, thus a feature.

If you were to send an email to all recipients even though some do not have a public key with you, they wouldn’t be able to decrypt the message. Often enough, such people will ask you to resend the mail. Maybe, they would provide a public key to you. However, you do not know, whether the recipient has been compromised. Thus, you would either not resend the mail (i.e. people still don’t get the contents) or you trust an unknown key (you cannot verify the key without meeting in person). If you do the latter, an attacker has all they need for a known-plaintext attack on all keys used in the original message. If any of the recipients has a weak key, they are compromised by your actions.

Long story short: Do not try to send mails that are encrypted for other people to people who don’t have a private key with you.