if this a web app, or is it something like outlook.com yahoo gmail gmx etc which are email addresses that you simply add to Thunderbird as (new) existing email addresses.

Hi - I have added the address to Thunderbird and have now manually transferred over the email addresses but they aren't appearing in the address book but they are there somewhere. The folders on the previous email server haven't transferred across.

You need to be more specific. Starting with answering Matt's question would help.

If you want your address book in Thunderbird, you will have to import it. That means exporting it from where ever it was. Was it in Gmail, Yahoo, Outlook.com, or your own domain name, or elsewhere?

Changing your e-mail servers doesn't automatically transfer anything from the old server to the new. Someone actually has to transfer them. How this is done will depend on the details you have not provided.

The folders were sitting in my xtra.co.nz email. Xtra is the same as Yahoo. Does that help?

E-mail: Set up your xtra.co.nz e-mail account in Thunderbird using IMAP. Copy all the messages and folders you have to Local Folders in Thunderbird. This will save them to your computer. If you want to upload those e-mails and folders to a different e-mail address, you will need to use IMAP, but upload the messages in small batches. IMAP is designed to use two-way communication with e-mail servers, but doesn't handle uploading to the server well for large batches or large e-mails.

Contacts: Log into Yahoo webmail for that account, and Export your contacts to a CSV file.

Import CSV into Thunderbird Address Book

1. Open Thunderbird's Address Book.

2. From the menu bar, selet Tools: Import. If the menu bar is not showing, press the ALT or F10 keys to show it.

3. In the Import window, select Address Books and click the Next button.

4. Select Text file (LDIF, .tab, .csv, .txt) and click the Next button.

5. In the "Select address book file" window, change the file type you are looking for to Comma Separated (*.csv), then find and open the CSV file you saved.

6. Now you will see the "Import Address Book" window like my attached screenshot. You need to manipulate the fields on the left to match the fields on the right, by selecting a field and clicking the 'Move Up or Move Down buttons. Not all fields will have information in them. For example, many people will only have the first name, last name, and e-mail address. So you checkmark only the fields that you want to import, and ignore the rest. When done matching the fields and checkmarking the ones you want, click the OK button.

Now there will be a new address book in the Address Book list, with the name of the file that you imported.

You can rename that address book, or drag-and-drop the addresses in it to other address books.