I'm using Thunderbird 60.3.0 and I have 2 problems related to "Reply All" for sending followups to emails that I had sent:

1) When I send an email to one recipient I sometimes need to send a followup to that same person. Once upon a time I could click on that email in my Sent folder, then click the "Reply All" button in the message header panel and the reply would go to my original recipient. Now that "Reply All" button is missing and this "Smart Reply" thing refuses to give me more than a single "Reply" button which would uselessly just reply to myself. I can go to "Message"->"Reply To All" in the tools bar at the top of my window to get that functionality but that's an annoying inconvenience vs the way things used to be where there was simply a "Reply All" button next to the "Reply" button in the message header panel.

2) When I send an email and blind copy recipients I sometimes need to send a followup to that same distribution list. When I click on "Reply All" the Bcc list is stripped (this definitely was NOT the case in older versions of TB) and I'm only allowed to reply to any recipients who were NOT blind copied. To work around this I have to do Message->Edit As New Message, then cut all of the original content, re-paste it back in as a quotation, and remember to change the Subject line to prefix it with "Re:". Obviously that is ridiculously annoying vs if Reply-All simply included the Bcc'd recipients as Bcc-ed again.

It looks like both issues first showed up in 2014:

1. <http://forums.mozillazine.org/viewtopic.php?f=31&t=2796815>
2. <https://support.mozilla.org/en-US/questions/1028980>

but I can't find any reference of a fix for them.