I've been a CEO and CTO, but usually in <100 employee companies, so as busy as I might've been, I could ask, "What's up with this?"
I think among all his possible sins, at Amazon scale, "?" itself wouldn't rank super high.
The larger issue is that Jeff's subordinates will then treat their subordinates in the same way. If this becomes common, it will extend to other behavior or communication. This will result in horrible company culture, where bosses treat their underlings like shit. Do not normalize this type of behavior! That is not good for employee retention, nor employee productivity/morale. It all comes from up top.
He held that every subsequent email in a long thread should start with, "Hello [name]," before the first paragraph. I thought that was reasonable for the first email, but when things got to the 3rd or 4th response, it was normal to just write your response, first paragraph starting on the first line.
Most of the company did that. He and I had issues. We never resolved this (I gave in on this, as I was trying to resolve our lack of alignment on many fronts), but I find it completely normal in most of the companies I've worked in since.
Especially since those of us who are emailing each other all day long are doing it over and over again, day after day, and getting the friendly formalities when we see other in real space, or on calls.
There's a passive aggressiveness to holding out for higher formalities when the cultural context is otherwise totally fine with shorthands that come with working and communicating with some people a lot.
Jeff's email is public and the original correspondence is copied in unchanged.
I'm not even convinced Jeff sent it as I don't think Jeff reads his public email. At a company of size > 100-1000 I don't think the CEO really has the bandwidth to stop and offer insight into the nature of the problem - does "please look into this" or "forwarding" or "cc xyz" or "?" really add much value?
In hindsight they were mildly fun - the forward chain would create a chain of accountability, starting with Jeff to Diego all the way down to an L4 in their 20s to fix a customer problem - each with their neck on the line but without much influence to solve the actual issue at hand.
It really was less an email and an alternative ticketing interface.
A single "?" could mean anything from "This looks interesting, could you give me some additional data." to "What the actual *&($ is this? Explain or your entire team is gone." A little more context would be helpful.
If he’s just innocently asking for the other side of the story, he should put together a complete sentence that demonstrates that, rather than sending a single ambiguous character that he knows could be interpreted as “you fucked up, fix this right now or you’re fired!”
The same way as non-CEOs? Write a 4 words sentence asking for more details?
Would not apply in this case however...
Someone who can't be bothered to type more than "?" might not bother to check for an answer either.
If it's important, they'll follow up.