User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.87 Safari/537.36

Steps to reproduce:

When new emails come in, they are not bolded, nor are unread emails. This happened when I updated my MAC computer to Catalina. I have version 10.15.1. I have version. My Thunderbird version is 60.9.1 (64-bit).

Actual results:

I am not able to keep up with my inboxes, as I can't tell which ones are new and unread (so that I can process them or delete the ones I don't need), and which I've kept in the inbox either to read later or answer.

Expected results:

When new emails come in, they should be bolded in the preview pane. Unread emails should stay bolded in the preview pane until I click on them or read them.

Likely bug 1563948. See the last few comments there please.