I need to move around 9,000 emails from a business Google workspace email to a personal Gmail account. I successfully exported all 9,000 emails to a Mbox file. I added the new Gmail account I want to move the emails to and the exported file to Thunderbird and it shows over 20,000 emails in Thunderbox (even though there should only be around 9,000). I have tried moving the email file to the new email account within Thunderbird twice now. Both times it shows like it is moving the 20,000 emails but when it finishes it only moves around 1,200 emails. How do I get it to import all 9,000 of the emails that are in the exported file?