I'm thinking I will add it as part of next upgrade. My domain has so few users and we are chill enough to work through email delivery issues. My understanding at the time was that the receiver verifies that the sender sent it.

My current delivery settings are strict so that only my server can delivery our email. I would think I could implement ARC in less strict manner and tighten it up as it becomes more common.

Does that seem reasonable? Any better ideas.