I use Thunderbird’s unified inbox as it is a very convenient way to manage multiple accounts. Yet there was a management account where the inbox was a huge pile of messages that needed to stay there but that I didn’t want to show in there unless I specifically clicked on that account.
No other guide on the first page of google results gave info on it, but here’s how you do it.
Right-click on the Inbox master node under which all the accounts’ inboxes are listed, then click on Properties, then Choose the selected folders to search, and un-check the Inbox of the account you want to hide. Then click on Update.
There you go.
Thunderbird 78.10.2 – this clearly described method does not work. That account still shows up listed under the unified Inbox after performing the indicated steps and then closing and reopening T’bird. 27 April 2021
thanks for reporting, alas I cannot confirm your findings as in my case thunderbird, which is 78.10.0 and saying it’s up to date, still behaves as it should, but I applied this modification back then and it was ported until today