When a folder is set to prefer HTML over Plaintext via the Folder-->Message Default Format menu, some messages with both HTML and Plaintext parts will display as HTML correctly, while others will first display the HTML part then switch to the Plaintext part very quickly. Using the global option, found in Settings-->Configure KMail...->Security->Reading->HTML Messages, will cause folders and messages with this bug to correctly display the HTML part without switching to the Plaintext part. Reproducible: Always
Marcus, your version has now long been unsupported. Is there any chance you can try to reproduce this with a recent version of KMail (>= 5.0 or >= 15.08.0)? If you are able to reproduce it, can you provide a message as an attachment that is displayed as plaintext, but should be displayed as HTML?
Using KMail 5.3.3 from the Fedora 25 repositories, I get the same issue. Sorry guys.
I guess that's not your fault ;) thank you for the feedback. Since I cannot reproduce it myself, I leave the bug unconfirmed for now. If you find an afflicted message that you can share with us, please consider uploading it as an attachment to this bug.
I also cannot reproduce this bug with KMail 5.9.2 (Qt 5.11.2 / KF 5.51) as well as KMail 5.14.40 (Qt 5.14.1 / KF 5.69). Marcus: Could you try again and possibly provide a message which fails for you (e.g. using File -> Save As, then redact any confidential information in a text editor and upload as an attachment to this bug). Otherwise I'm afraid this will be very hard to fix.
Dear Bug Submitter, This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information as soon as possible and set the bug status as REPORTED. Due to regular bug tracker maintenance, if the bug is still in NEEDSINFO status with no change in 30 days the bug will be closed as RESOLVED > WORKSFORME due to lack of needed information. For more information about our bug triaging procedures please read the wiki located here: https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging If you have already provided the requested information, please mark the bug as REPORTED so that the KDE team knows that the bug is ready to be confirmed. Thank you for helping us make KDE software even better for everyone!
Sorry for the slow response. I'm not able to reproduce this any more either. If I find a failing E-mail I'll try to scrape it of personal information and attach it to the bug.
Thanks for the response. Let's set the status to RESOLVED for now, but feel free to reopen if you happen to come across a failing mail.