(2) 'Other' and the Archive folder on the mail account.  This latter choice (2)  seems to be an Archive folder that thunderbird has set up, and, in fact, no matter which option I select (1) or (2), when I subsequently Archive an email by clicking the Archive button, the email goes into the folder that I think thunderbird has automatically set up. (The 2 choices show different icons for the folders.)  

I'd like to set up an archive folder to move old emails into. I still want to be able to access the folder, and have it part of the search process. When I go into the account settings, and Copies and Folders, there are 2 choices for which Archive folder to use. Under "Keep message archives in", I can select either (1) 'Archives folder on' and the mail account name. OR I can select (2) 'Other' and the Archive folder on the mail account. This latter choice (2) seems to be an Archive folder that thunderbird has set up, and, in fact, no matter which option I select (1) or (2), when I subsequently Archive an email by clicking the Archive button, the email goes into the folder that I think thunderbird has automatically set up. (The 2 choices show different icons for the folders.) Is there a difference between these 2 choices and how they function? (I have an imap account.) I'm not sure which one to select, or what difference it makes? Any help would be appreciated. Thanks.