Here is the fastest way to back up and restore Thunderbird mailboxes to the local machine. this method requires using this third-party tool, the
MacSonik Thunderbird Backup Tool. This software has the advantage of migrating Thunderbird mailboxes to numerous email clients, for example, Gmail, Yahoo, IMAP, Hotmail, AOL, Opera Mail, Hostgator Email, and so on, in batches. It facilitates removing duplicate emails based on From, To, Cc, Bcc, Subject, and Body. Moreover, the tool allows users to Thunderbird emails to PDF, PST, EML, EMLX, DOCM, DOCX, PNG, JPG, MSG, HTML, MHTML, GIF, etc.