My suggestions assume IMAP. If POP, these are not the right steps, so let me know. # Click account settings and click the 'advanced' button under the synchronization&storage pane to verify that all folders can be downloaded # click File>offline>download from menu bar (if menu bar not visible, press alt key first) # click help>troubleshootinginformation # scroll to 'profile folder' and click 'open folder' # exit thunderbird # click to imapmail\<IMAP account folder> # locate the message files, represented as two files, such as inbox, inbox.msf, sent, sent.msf # COPY (not move) the message files (excluding the msf files) # Click Mail\Local Folders folder and PASTE there (rename first if the paste would overlay an existing file) # restart thunderbird and check that all the content is there. You have now captured the complete account to PC. # setup the new account and, for each desired folder, select all messages and click 'COPY to ... (NOT MOVE). If many messages in the folder, you may need to COPY a small number at a time, as IMAP was not desired for high volume uploads.. Another approach would be to set up a manual filter to copy the messages of a folder. # after the upload to new server, recheck that all content is there # pour a glass of wine and celebrate. ok, make that two glasses