Mozilla is the maker of the popular Firefox Internet browser, but the company also provides users with an e-mail client. The Thunderbird e-mail client uses the LDIF file format to store the addresses you add to your address book. If you already have contact information stored in the widely used MAB file format, you can import that data into Thunderbird and save yourself a lot of repetitive typing.
Open Thunderbird and click the "Tools" menu. Choose "Address Book" from the list of options.
Choose the "Tools" option and then "Actions for Address Books." Choose "Import address book from MAB."
Shut down Thunderbird and restart it. The addresses stored in your MAB file will now be available in your e-mail program.