An option is to move everything at once, but I infer you want to just move pieces. To do that, - click help>groubleshootinginformation - scroll to 'profile folder' and click 'open folder' - exit thunderbird - you are now in the profile - for IMAP folders, click the imapmail folder and then the <IMAP account> folder - here, you should see the message folders. COPY the files by name, but ignore the .msf entries - for POP folders, click the mail\<POP account> and COPY the desired files, again ignoring .msf entries - for Local Folders, click the mail\Local Folders and do as above - now that you have copied them, repeat all the above on the receiving PC

For addressses, you can copy the entire addressbook using above steps. they are abook.sqlite and history.sqlite. both go in the root folder and you would paste over the top of existing files. I know of no way to move specific email addresses.