When composing a new message, selecting "encrypt message" will cause attachments to be also encrypted. This is the correct, expected behavior.

However, if encryption is not manually selected and a message comprising attachments is sent AND the option "automatic encryption" ("Nachrichten möglichst automatisch verschlüsseln")is selected and the key of the receiver is known, a pop-up is displayed, asking whether you want to encrypt the mail. This is also correct.

HOWEVER: if you select yes, kmail will only encrypt the message body, not the attachments and will send out the unencrypted attachment without asking further questions.
 
Expected behaviour: attachments are also encrypted

Reproducible: Always

Steps to Reproduce:
1. In the settings, under security, select "automatic encryption" ("Nachrichten möglichst automatisch verschlüsseln")
2. Compose a mail to a sender having a known gpg key
3. Attach a file to the message
4. send the massage, when asked whether you want to encrypt the message, select yes

Actual Results:  
Message body will be encrypted, attachment will be sent in clear , defeating the purpose of sending encrypted mails

Expected Results:  
Message body ant attachments are encrypted