Your contact lists are exported and saved in a comma-separated (.csv) text file format.
Exporting Contact Lists
Go to Preferences>Import/Export
In Export, select the Type as Contacts
Select the contact format to export the contact file as.
Windows Live Contacts
Outlook contacts
Account contacts (this keeps the contact information in the same format is it is in)
Thunderbird
Outlook 2003
Yahoo contacts
In Source select the contact list to export. Click OK.
Click Export.
In the dialog that opens, select Save File and select where to save the file. Click OK.
The contacts file is saved as an .csv file, with the contact information organized for the format you selected.