I have been using Mozilla's Thunderbird email client for a long time, so of course I downloaded and installed the latest version of it today. It is a piece of crap. I like to filter out the spam before using my desktop client, so I tell the client not to check for and download messages from the server other than manually. Thunderbird ignores that setting and checks on startup and every ten minutes regardless of the settings.
At least I did finally get Flash installed on Firefox.