3.3. Message Disposition Notification
MDN is a generalization of what is commonly called "read receipt". The sender of the message requests a disposition notification to be sent and the receiver's mail program generates a reply from which the author can learn what happened to his message. Common disposition types include "displayed" (i.e. read), "deleted" and "dispatched" (e.g. forwarded).
In KMail you can request notification when people read the mail you sent, and KMail can send notification when you read mail sent to you with notification requests.
To configure this KMail in Kolab mode new feature, point to Settings->Configure KMail and in the Configure KMail dialog click on the Security icon. The General view of the Security and Privacy Settings form should be displayed.
As shown in the above view, several options are proposed to the user in order to configure hers Message Disposition Notifications
Ignore:All requests for disposition notifications will be ignored.No Message Disposition Notification will be sent automatically. This is the recommended setting in a security point of view.
Ask: Answers requests only after asking the user for permission.
Deny: Always send a "denied" notification. The author will still know that his message has been acted upon.
Always send: Always send the requested disposition notification.The author of the message will know what happened to it. This option is strongly discouraged in a security point of view.