Suddenly, for some reason, some of my received emails are beginning to appear with garbage characters at the top of the file. I’ve searched the forum here, and the answer always seems to be “you’re using the wrong font” or “the sender is composing the HTML incorrectly.”
I’ve traced the problem to the X-JNJ: body and the way it’s interpreted. eM Client’s MIME parser terminates the header block prematurely when it encounters a folded X-JNJ: header with a long base64 value. Subsequent headers (Content-Type, Content-Transfer-Encoding) are never processed, so the base64-encoded body is displayed as raw text. The mime parser sometimes “fixes” itself if it runs across a mime boundary it can recognize. Reproducible with messages from [J&J mail system]. The message renders correctly in Outlook, Thunderbird, and iCloud email. Affects both v10.4.5674 and v11 beta (11.0.473), confirming this is in the shared MIME parsing layer, not the HTML renderer.
This is definitely an eM Client error, not malformed HTML and since it appears in both 10.4 and v11 it doesn’t appear to be Trident-related. I can provide emails that fail the mime parsing separately (out of public view).