I use Thunderbird to control my Yahoo account (among others). Today we were notified that Yahoo is changing its authentication procedures. I've read the Thunderbird instructions on how to comply (https://support.mozilla.org/en-US/kb/thunderbird-and-yahoo), but prior to doing it, I'd like to somehow save the entire account just in case something goes wrong. Note: this is a very old, but in continual use, account. I have dozens and dozens of folders, probably thousands of messages. I know I can painstakingly download each folder to an offline storage spot, but is there any way I can simply download the entire account or some other way archive it just in case something goes wrong?