SUMMARY Mails with a "Date:" tag in header like "Date: Mo, 25 Aug 2025 00:01:04 +0200" are sorted and displayed as date 1970/01/01 Tags like "Date: Tue, 19 Aug 2025 00:01:13 +0200 (CEST)" are fine. No other tested mail client (Thunderbird, Evolution, K9) is having this issue. Looks like that RFD2822 doesn't care about the one or the other. https://datatracker.ietf.org/doc/html/rfc2822#section-3.3 STEPS TO REPRODUCE 1. Send yourself a mail with the mentioned "Date:" header SOFTWARE/OS VERSIONS Linux/KDE Plasma: 25.08.0-1 Qt Version: 6.9.1