I have a set of old thunderbird emails that I saved previous. For example, I saved the entire .thunderbird/old1900.default/ folder. Now I would like to add the emails from that profile to my current Thunderbird installation. I don't want to over write my existing profile. I just want the Inbox, sent, etc email messages from my backup to be viewable in my current profile. I tried copying the old .thunderbird/old1900.default/Mail/abcd.com folder into my current .thunderbird/new2015.default/Mail folder and it didn't work. I also tried moving it into the .thunderbird/new2015.default/Mail/Local\ Folders/ and the folders show up in thunderbird but message are not detected. I also tried the menu "Tools/import" and selecting "Mail" but then the "Please select the type of file that you want to import" windows is blank. Is it possible to open the backup emails in my current profile?