Although there are manual methods but because of the multiple limitations the migration becomes risky for important emails and large mailbox. However you can use the CubexSoft Thunderbird to PST Converter Tool which is a professional utility specially designed to convert bulk as well as individual Thunderbird emails to PST without losing any attachments and metadata. The tool offers direct file conversion, batch folder export, preserve the folder structure, multiple output options, and automatic mailbox detection, and also supports Windows and Mac OS. The tool also has a user friendly interface which let the users navigate throughout the process easily. It also a demo trial which let the users migrate up to 20 Thunderbird emails from the mailbox for free.