Run Thunderbird again. The downloaded contents of your Gmail account will appear under Local Folders in Thunderbird. If you use a Mac, you can import the MBOX file.
Thunderbird Help.
Collect credible solutions from Thunderbird technical support number, Dial 1-800- 563-3020 Toll Free for Mozilla most usable application custom setting or to know.
Save your Windows Mail contacts to a CSV file that lets you migrate and copy them to most other email programs and services. The most common email client is probably Microsoft's Outlook. Outlook allows you to create a backup file of all your email messages and contacts.