If I'm composing a list in an email message and I hit enter twice in a row, i.e., the first time to terminate the current list item and the second to cause a blank list item, then the message editor should turn off list mode, just as every other WYSIWYG editor does nowadays. Instead, it'll keep creating empty list items as long as you keep hitting enter. This is broken.
Thanks for reporting this. I moved it upstream [1] where we will track the issue. [1] https://bugzilla.gnome.org/show_bug.cgi?id=515844