Now that it's resolved I'm also not sure about the ordering of what went wrong or why. So I'll just describe all the issues and my fixes, maybe it'll help someone.
My blog runs on Amazon's EC2 and uses their SES to send emails. This requires verifying my domain, and the way they want to verify domains is by you adding a TXT entry in your DNS records. When I noticed my emails were dead, I went to the SES console and discovered my domain verification had somehow been expired. I went to my domain administration page, and sure enough the TXT entry I had since 2012 or so was still there. A key of "_amazonses.thejach.com" and a value of some b64 key. I told Amazon to reverify, and went on a business trip.
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