Imported from Thunderbird, lost all Sent messages

I imported everything from Thunderbird – all my folders came in, except for Sent messages. Is there a way to go back and import *just* the Sent folder from Thunderbird?

Thanks for any help.

there is option for importing folders.
File-> Import -> Import from Thunderbird and then choose option “Import selected folder”, click Next.
Choose destination and click next. Expand account, check Sent folder and click Finish.