Hey there! It looks like you're encountering a bit of a glitch with Thunderbird's email grouping and titles. No worries, we'll get this sorted out. The numbers in the grouped list titles might be a bit wonky due to some underlying issues. And as for the "Today" turning into "Old mail" – that sounds like a quirky bug too. To address this, let's try a couple of steps. First, make sure you're on the latest version of Thunderbird. If you are, try restarting Thunderbird or even your computer. If the issue persists, you might want to consider repairing your Thunderbird profile. Go to "Help" > "Troubleshooting Information" > "Open Folder" to find your profile. Rename the file named "places.sqlite" to "placesOLD.sqlite" and then restart Thunderbird. This often clears up odd display issues. If you're comfortable with it, you can also try creating a new profile to see if the problem persists there. Give these steps a shot, and hopefully, your Thunderbird will be back to smooth sailing. If not, come on back, and we'll dive deeper into solving this for you!