This guide has listed three basic ways to import Thunderbird emails to an Outlook email account.
If you need to transfer a few messages, you can drag and drop them into Outlook manually.
If you have many messages in different folders, you can connect an optional IMAP account to Thunderbird and Outlook. Then export Thunderbird emails to this account, and after, synchronize it with Outlook.
More quickly and productively, you can transfer mail using the handy
Thunderbird to Outlook converter, which converts MBOX data files to PST format. This tool offers advanced features when transferring data.
Storing data in PST files is convenient for mailbox archiving. PST data files can be
merged with each other,
moved to other accounts, and converted to other formats like
HTML,
PDF,
DOCX.