KMail version: 5.2.2 Using: KDE Frameworks 5.23.0 Qt 5.6.1 (built against 5.6.1) The xcb windowing system KMail doesn't display the blue header (To, From, Subject, Spam Score, User Agent) in the message preview pane or separate message window. This affects HTML and plaintext mail alike. The menu View > Headers is also empty. When launching kmail from command line, the following string printed to stderr: log_messageviewer: trying to writeMsgHeader() without a header style set! If I remove ~/.config/kmail2rc, the bug still persists. Reproducible: Always Steps to Reproduce: 1. Select any message in folder view. OR: 1. Open any message using double click. Actual Results: Only message body (text or HTML) appears in preview pane and message window. Expected Results: A header with From, To, Subject and optionally other fields (user agent, spam score) in message preview pane and message window.
Apparently, themes are now in a separate package, e.g. kdepim-themeeditors for Debian. Installing it fixes the headers.