From the bug report , which also has a screen shot mock up "This would make it easier to identify the folders of diffrent mail accounts. This would also make sense for the top account nodes."
We understand that user desire for a Thunderbird branded calendar is strong. However there are compelling time sensitive, important feature improvements and technical debt which must take priority before considering a project as large as a new calen...
Thanks for all the interest.This is on the roadmap to be worked on this year, and hopefully available for testing but might not be delivered in production this calendar year. We will update the ticket towards the end of the year.
Great news. This is fixed by Bug 242300 - New/unread messages in thread are not obvious enough (bold vs. underlined) in a current release. And will appear in the next esr release 153 in a month.
