I've tried to self-host email for my domain a couple times over the past few years, and I always end up falling back to a paid host for this reason; I rarely use email these days, but when I do (or usually when I'm expecting an email from a recruiter or other business-related sender) I need some sense of confidence that it will go through correctly. The lack of ability to confidently send via self-hosted setup definitely feels intentional, which sucks.
Great article btw!