I can’t recommend Migadu. I used them for a year, and I spent many hours dealing with delivery issues and somewhat frequent unannounced outages/upgrades which go unreported. Spam filtering is generally broken and ignores whitelists. They tend to respond to about 50% of support emails, the last one being rather petty when I left the service.

I should have seen the yearly plan fee as a sunk cost and moved on sooner. Hope this helps someone else.