I run my own archive methodology in Thunderbird. In the .thunderbird path with thunderbird not running I usually rename the INBOX to Inbox_year, for example Inbox_2019. I then make a new Inbox and restart thunderbird. I do the same with the SENT mail directory. I am quietly confident that this is what I have done for more than two decades. The process is NOT working at the moment. I don't really know why and I cannot find any documentation that will help me link or directly attach the getting of mail to the new inbox. It is linked to the moved folder. That is new mail is put into the Inbox_year box and not the standard inbox. I admit to not under the presented icons. The icon associate with the Inbox and the Inbox_year just move is an envelope with an unsealed flap. A;; the other icons are folder icons. I hope that my description is sufficient. Thanks and regards Peter