I switched to M365 as my provider a few years back as my emails kept being flagged as spam.

I've done it for decades, but I don't know much beyond the basics of email hosting tbh, however my understanding is that these days email coming from self-hosted servers carries a much higher spam/junk risk and so often automatically marked as spam.

Maybe there are ways to avoid this happening, but when a few clients all reported that they were not receiving my emails I didn't have much of a choice but to switch.

I would also be interested in self-hosting but have limited understanding of what would be required to ensure my email does not get flagged as spam.