Step 1: Open Thunderbird. The icon should be found on your Desktop or in All Programs > Mozilla Thunderbird.

Step 2: Select Tools > Address Book.

Step 3: Select the desired Address Book. Note: Make sure that you are selecting a specific address book. The selection by default is set as "All Address Books" and exporting this way will result in a blank file.

Step 4: Select Tools > Export... Note: If you do not see the Export option, click View > Toolbars to turn this option on.

Step 5: Select Comma Separated (*.csv) from the Format drop-down box.

Step 6: Choose where you want to save the exported file, give the file a name, and click Save. Use the CSV file to import into other email providers, such as Gmail, to move contacts.