Conversely, I have a pre-MS hotmail address and verification emails never arrive for any number of services.

MS spreads it's toxic protection in every direction.

When I requested to escape the sandbox, my request was granted in nine hours...admittedly, this was six years ago, but it looks like the process is the same (https://docs.aws.amazon.com/ses/latest/dg/request-production...).

From what I've gathered it's highly dependent on region, tried a few others but that probably set off some flags for them even more.

Send a dozen emails weekly, in the end felt a bit ridiculous begging. It's a generous free service so I can't complain.