Apologies, but in my memory Thunderbird is just the new name for Netscape Mail. And Netscape mail, I believe, is older than Outlook.
I still have folders in my current Thunderbird that I created in Netscape (for example the 1996 folder that contains all mail from 1996).
I still got some bookmarks carried over from Navigator... though I bet 95+% don't work anymore.
Apologies, but in my memory Thunderbird is just the new name for Netscape Mail. And Netscape mail, I believe, is older than Outlook.
I still have folders in my current Thunderbird that I created in Netscape (for example the 1996 folder that contains all mail from 1996).