Version: (using KDE 4.2.4) Installed from: Debian testing/unstable Packages Some strange MUAs (lotus for example) sometimes fail to correctly specify the content-type of the attachments in mail messages. In these cases kmail prompts to the user to select the application. I think it would be better if in case of application/octet-stream kmail would use the file-magic to discover the real content type of the file and propose the associated application.
*** This bug has been marked as a duplicate of bug 199537 ***