Microsoft 365 is corporate business email for corporate businesses. If you're a corporate business, you're already using it, and if you're not then you probably don't want to talk to anyone who's using it anyway. Even if you could pass their filtering, they'd just manually ignore your emails because they only want to talk to corporate businesses.
Maybe persons and families should stop using email services that refuse to deliver them the emails they want. If I personally use /dev/null as my inbox does it become your problem to ensure mail delivery?
I recommend that whenever you know someone cares about receiving an email much more than you care about them receiving it, just send it. They'll do what they have to, and this way we can weed bad providers out of the market. Some websites with email verified sign-up have a simple FAQ to let you know what's causing the problem.
Most people at e.g. Oxford and Cambridge (and, I suspect, many other universities) use their university emails for a fairly wide variety of extramural correspondence, and are stuck with M$ as the provider, alas.
