If your iCloud.com (or, in my case, me.com) email isn’t sending...
…and is stuck in outbox purgatory, you are not alone.
I reached out to Apple support this evening and they confirmed there is a current outage for “some users” and that engineers are on it.
So if you are getting the same error (eventually, it can take a while), rest assured, the right people are looking into it.
Hopefully.
Because man, do I hate to crack open my secondary Gmail account.