By teh way, the use of mailto: URLs and ShellExecute is not strictly "automation" in the sense of COM automation, which is done by first creating automation server like you can also build with VFP when you design a class to be olepublic.
So, in short, COM automation would first create an outlook instance with CREATEOBJECT("Outlook.Application"), executing a mailto: URL is just making use of the MAPI meachnism this is triggering to start the mail client defined as Windows standard mail client and creating a new mail item on the standard mail account. It's also automatic, so in that sense automation, sure, but it's not the gold standard COM automation you could use.
According to
this version of outlook indeed loses the COM automation available for the standard Outlook Desktop applications. It's instead based on WebView2, like the Edge browser and this article expects there to be a javascript based automation mechanism.
Anyway, when you build a new mail client, and I'm sure MS has reused a lot of the Outlook codebase, no matter if the UI and interface changed, at least mailto: URLS should work, the ShellExecution of mailto: URLs also worked with Outlook Express, if you remember that as the small (and free) brother of the fully fledgbed Office Outlook, mailto: alsop worked with Windows Mail, if you also remember that - and I think that also still is available - as part of the Windows Live / Windows Essential. We've already been through a lot of ups and downs on Microsoft deciding for and against such bundles of software that enable private users to have all the essential functionalities they need without having Office or even an Office susbcription. And indeed the pressure of the free Google suite of docs/sheets/gmail and other such suites like OpenOffice or LibreOffice and more.
I just took a stab at googling Microsoft revenues and see MS makes most money with their cloud computing platform, more than with sales of Windows and Office combined. So this software landscape change seems to me a step to get everything more integrated into the cloud (web) than to the desktop, basing that Office on WebView2 is clearly a step in that direction. We'll likely see a shoft away from COM in more aspects in the coming years.
Still, it shouldn't even affect you with not using COM automation but the mechanism to trigger the standard mail client. That's a loss in quality, to me. They might have their reasons to bury COM, but when you undermine such mechanisms that's putting users into a situation where they need third party software that still supports standards Microsoft even was involved with defining and integrating into Windows and their own software suites, even those free express versions MS also always offered.
Chriss