http://kb.mozillazine.org/Archiving_your_e-mail This is one method and good for moving all to specified folder especially if in 'Local Folders' > 'Archive' > 'year'. In other words archiving outside of mail account. But I'm thinking that if you keep archived emails in same mail account then perhaps it would be searching those as well. But bare with me and keep reading.... 'Menu icon' > 'Find' > 'Search Messages' Select mail account select 'Search subfolders' 'Match all of the following' 'Age in days' 'Is greater than' 365 Move to a selected folder. However, if you also add another condition. 'Age in days' 'Is less than' 730 then perhaps it should not pick up anything in the 'Archive' folders. I've just done a test on my accounts and it did not pick up anything in my email account Archive folder. YAlternative option: Use a Message Filter. 'Menu icon' > 'Message Filter' >'Message Filter'. choose mail account click on New Give filter a name: Annual Archiving Select 'Archiving' 'Match all of the following' 'Age in days' 'Is greater than' 365 'Move message to' and select the Archive and year folder. click on OK then select that filter. 'Run selected filter on:' Choose which folder to run on. click on 'Run Now' Check the folder to ensure all moved ok. Run selected filter on another folder. This is still manual and each year you would need to update the filter to specify correct folder, but may be quicker than selcting folder, sorting by date, highlighting everything older than a year and clicking on 'Archive'. Still not exactly an auto archive when opening Thunderbird, but may improve the current method you are using.