Imap account folders can only display whatever is on server. It's really designed to store emails on server and then show a view of whatever is on server. You can download headers only or download full copies of emails, but because all these imap folders synchronise with folders on server, you cannot regard them as truely independent of the server. When ever you want to open, move, delete etc etc any email in an imap account folder there is much jibber jabber between the imap account and the server to keep both synchronised. However, it sounds like you want to keep copies of emails that are completely independent of the server. First: make sure you are actually downloading full copies not just headers. Account Settings > Synchronisation & Storage Info here: https://support.mozilla.org/en-US/kb/imap-synchronization#w_configuring-synchronization-and-disk-space-usage Second: Create suitably named folders in 'Local Folders' mail account Third: I would advise that you do not 'Move' emails into 'Local Folders' mail account because if something goes wrong then you could lose the email altogether. Note: 'Moving' an email from an imap account folder into a folder outside of the imap account will cause emails to get deleted off server because folders synchronise with server folders. Advise you to Create Message Filters to get 'Copies' of emails and put the Copy in a selected folder in 'Local Folders' account. '''Tools > Message Filters''' See info here: https://support.mozilla.org/en-US/kb/organize-your-messages-using-filters Once you have created the filter - make sure it is selected as enabled. Remember filters operate in the order listed. Suggest you enable the filter log as well as it may prove useful. Bottom right click on the 'Filter Log' button It opens in a new window - select the checkbox 'Enabled the filter Log' then click on 'Close'