Since your question was specific, I'll try to respond appropriately: - exit thunderbird - locate the Local Folders in the old profile, normally in Mail\local folders folder - they will normally be sets of two (e.g., foldername, foldername.msf - copy them to the Mail\Local Folders folder of the receiving profile - the addressbook is abook.sqlite, unless you haven't updated in several years, in which case it would be abook.mab. click tools>import>import from a file and follow the prompts.