To drive the point about this being fundamentally unsolvable home, imagine a variant of this scenario.

I could write an email that is directed towards that person, that says WE ARE STUCK IN THE SERVER ROOM AND THERE IS FIRE STARTING. PLEASE CALL 911 AND ALERT YOUR BOSS.

Would you want the human assistant to just dismiss this as a prompt injection attempt? Or ignore it because they were told to treat e-mails as data and never act on them?

I would have had a chat with my recruiters during interview, or with my new superior right after the change in position:

"life is risk, there are a lot of benign normal evolution paths, but occasionally there are potentially costly dangers. people are directed by fear. you and I don't steal because we were terrorized about the existence about police and prisons as children. sadly fear can also be abused as a control vector, things like wars, extortion, ... in a job context I predict this would manifest as a kind of 'emergency' call to action. please provide me with a method so that at any future time under your leadership I would be able to verify the then-current employment status and authority level vis-a-vis a breakdown of actions/powers of anyone contacting me with a real or concocted 'emergency', preferably as a flowchart to maintain low reflex latency in true emergencies. Also provide me with formal proof that each situational reaction you require from me is in fact legal to take vis-a-vis the law"

Why are the only options dismiss or ignore? Another option is to raise the message to your boss asking what to do.

If there is a fire and a risk to life, you don't want any delay.

Then don't send an email? Emails are async in the first place.

Sometimes it's the only thing you have available. Like IDK during a fire in a basement server room, where the only connected device available is a laptop with wired connection and an open inbox.

Because you know, you tried IM but "sekhurity reasons" demanded passkeys or 2FA with your phone that's not connected. Sorry, getting off-topic here.

Sounds like a story from the IT crowd rather then real life situation.

You're saying that people fall for phishing because scammers invent completely unrealistic scenarios that would never happen outside TV shows?

I am saying it is unbelievable scenario and yes, I want the person dealing with it ignore it as such.