re :The address book has 3 sections As a guess, are you talking about the left 'Directory Pane', which displays the list of address book names? eg: 'All Address Books' > 'Personal Address Book' > 'Collected Addresses' You will notice that a right click on any of those address books does not offer the 'Delete' option and the 'Properties' will not allow you to change it name. This is because they are the default address books. Internal code has set them up and that code is intertwined in other sections of Thunderbird. They are not optional from a viewing point of view. They are optional in how you wish to use them. It is possible to change the name of 'Collected Addresses' ; but seriously, what is the point. It will still be displayed. 'Not Applicable' is inaccurate in it's name. 'Not Used' may be more accurate. But in reality you can still drag any contact into that address book and it is still the default address book for collected outgoing mail , so if you do not want that to occur please check the Options for this. Changing name: * Close Address Book. * 'Menu icon (3 lines)' > 'Options' > 'Options' > 'Advanced' > 'General' tab * click on 'Config Editor' button It will tell you to be careful. * In top search type: '''Collected''' * Look for a line like this: '''ldap_2.servers.history.description''' * double click on that line to open a small window which allows you to enter a string value. * Clear the contents and type : Not Used * click on 'OK' * close the 'about:config' window - top right 'x' * click on 'OK' to save and close Options window. 'Collected Addresses' is an address book which can be used for automatically collecting any email address you manually type into a 'To' field when sending an email and that email address is not in an address book nor do you want to add it to Personal Address Book. You can choose to not collect any email addresses you use when sending or use the 'Collected Addresses' address book or another address book of choice. This is set up here: * 'Menu icon (3 lines)' > 'Options' > 'Options' > 'Composition' > 'Addressing' tab * 'Automatically add utgoing email address to my:' * uncheck the checkbox to stop collecting email address * or select an address book by choice. * click on 'OK The 'All Address Books' is not a real address book. It is a virtual address book used when you want to view all contacts in all address books collectively perhaps for a search or to see if a particular contact is in more than one address book for updating purposes. As you can see from the left arrow beside the name 'All Address Books' - it is the top level, the 'Personal Address Book' (and all other address books) is arranged within it. You can create other address books if required for organising. eg: Some people keep the 'Personal Address Book' for Family. They may have another address book for 'Friends' Or other address books for any specific social club or business etc. they may use the 'Collected Addresses' for one off emails which they might need to access again like councillor or a shop email address or a website webmaster etc. It is like a history of addresses used.