MAB, short for Mozilla Address Book, is a file extension used by Thunderbird and SeaMonkey. It is also a file format for Netscape and other Mozilla mail programs. MAB stores both personal and business contact information which includes names, email address, phone numbers, home address etc.
Mozilla Thunderbird, SeaMonkey create two default address books known as Personal Address Book (abook.mab) and Collected Addresses (history.mab). Besides, if other address books need to be created then they will be named as abook-1.mab or abook-2.mab. Thunderbird address book file extension is mainly classified into 3 categories: abook.mab, history.mab, and impab.mab.
abook.mab: It is a default folder known as Personal address book. This abook.mab file format is used to save individual’s personal contacts.
history.mab: It is a default folder known as Collected Addresses which keep track of all the gathered contacts & addresses.
impab.mab: IMP (imported) AB (Address Book) stores contact information or addresses that have been imported to the email programs.
Error message: Unable to load address book file abook.mab. It may be read-only, or locked by another application. Please try again later.
This error occurs when users download thunderbird-38.5.1.tar.bz2 file from Thunderbird download site and some file gets missing within tar file. Try the following steps to fix the issue of .MAB file extension: