how much data you have ?
If it is manually manageable, this is what I did:
created an imap account
moved /dropped folders and emails from thunderbird to imap account
closed thunderbird.
opened outlook configured it to use imap account
dragged and dropped folders back to personal /local folders.
later changed outlook account settings to pop3 /smtp
for me data was only around 2GB, with around 50 folders, imap server was local, so everything was completed within an hour.
by the way, am using thunderbird only now.