Ask Paul: January 26 (Premium)

After a two-week absence, no one should be surprised by the epic length of this week's "Ask Paul." Let's dive right in.
Yubikey part 3
Just a quick follow-up here: Way back in December, Polycrastinator asked me about Yubikey and why Microsoft doesn’t support the FICO U2F standard as others do. I told him at the time that Microsoft wouldn't respond to a question like that over the holidays, and then he pinged me about it again the following week.

Long story short: I've now asked twice, and I will get back on this as soon as I get an answer. I've not forgotten you. :)
Excel v. default email
Simard57 asks:
When I use Excel and select Send by Email, it defaults to Outlook - I do not have outlook installed, I use Windows 10 Mail & Calendar. Can this be configured someway to work to use the Windows 10 Default program instead of the Office Default? If not, where can I change the Office default email program?
As someone perhaps inadvertently alluded to in the comments, I'm not an Excel expert. And, sure enough, I don't see a way to configure it to use another email application.

But why not just turn this on its head? I realize it may be slightly more efficient to try and send an Excel document from that application. But is it really that hard to open Windows Mail, create a new email, and then attach it from there? In thinking about this, that's how I attach everything: I start with the email application, not the app I used to create the attachment.

If your brain isn't wired that way---we all do things differently---you might consider sharing the document via some other means. In Windows 10, for example, there is Share functionality built right into the shell. So you could right-click that document and choose "Share," and Windows Mail is one of the options.

Speaking of which, if you save your documents to OneDrive or OneDrive for Business, you can use the Share functionality in Excel 2016 to share it with others that way. Note that you're sharing the live document, however. If you choose "Send as attachment" from the Share pane, yep, Microsoft Outlook is the only choice.

I'm surprised Office 2016 doesn't natively support Windows 10 Share. That is a curious oversight.
The real risk from Spectre and Meltdown
Polycrastinator asks:
I'm still having a hard time quantifying the risk of running a system that's not been patched for Spectre in the BIOS. For a desktop or laptop, is this something you'd say you shouldn't worry about, or is the risk great enough that you should stretch the finances to replace an older system?
My understanding is that there are no known attacks that are using these flaws. But that is only a matter of time, and it's pretty likely that some are in the wild already, but are undetected. Regardless, the risk, for now, is low, I think.

Obviously, keeping your systems up-to-date is generally good advice. I have always, as a matter of course, installed whatever BIOS/firmware updates that my PC makers h...