I recommend using the MacSonik Thunderbird Backup Tool, you can easily backup and restore Thunderbird mailboxes to the local machine. Using this utility, you can export to Gmail, Yahoo, IMAP, Hotmail, AOL, Opera Mail, and HostGator Email. Its Date range feature allows users to select the start and end dates to export the emails between them. Moreover, the tool allows users to Thunderbird emails to PDF, PST, EML, EMLX, DOCM, DOCX, PNG, JPG, MSG, HTML, MHTML, GIF, etc. Additionally, it facilitates removing duplicate emails based on From, To, Cc, Bcc, Subject, and Body.