>That seems to require a Microsoft account and that's something I neither have nor want. I believe sending emails has to work without having to register an account for each provider you're interacting with.

Yes it does require signing up with them. I see that you’re taking a moral stance on this so I guess the best action is to just ask people to not use Microsoft email products, which is perfectly reasonable in my opinion.

For what it’s worth, I do have an account with them and I am very small scale and don’t have any deliverability issues with Microsoft.