When you say 'I lost everything' do you mean you also lost the 'Thunderbird' profile folder which contained all pop data? Mac OS X Profile folders are located here: * ~/Library/Thunderbird/Profiles/<Profile name> The tilde character (~) refers to the current user's Home folder, so ~/Library is the /Macintosh HD/Users/<username>/Library folder. The 'profile name' folder is usually something like this xxxxxxxx.default where the x's are various letters and numbers and it will be in the 'Profiles' folder. Check to see whether you have two 'profile name' folders. Pop account info will be here: * ~/Library/Thunderbird/Profiles/<Profile name>/ Mail/pop mail account name If you only have the one profile name folder, do you have two 'pop mail account' folders, one with an additional number ? Previously, your old pop account downloaded emails from server, but did you have settings to 'keep messages on server' set up in the Account Settings > Server Settings? Is the new pop account set up to 'keep messages on server'? If you logon to your webmail account via a browser, do you see all the old emails or is it empty ? What server are you using eg: gmail ? Do you have a backup of ~/Library/'''Thunderbird''' folder ?