As per subject, around ~15 of Jan, images in e-mails started to be shown in e-mail viewer with 100% width, redgardles of ''max-width:$px''. Worked as a charm for like 2 years. I have no idea if this is a bug - I didn't see any info in release notes that something was done to viewer and quick jump into bugzilla just gave this topic: https://bugzilla.mozilla.org/show_bug.cgi?id=1912242. Changing [style="width:100%; max-width: 450px;"] to [style="width:450px; max-width: 450px;"] seems to work, but thats not the case. When creating new message with exact same html code everything is fine. PS. I have no idea how to report a bug in bugzilla, heckin' overcomplicated if you ask me, so i decided to start here and if nothing can be done, escalate it there.