In this case, actually, yes, you should just get over that. It's not a threat, it's an insult, designed to elicit an emotional response. The only thing you can do to take away that power is get past the emotions and move past it.
That doesn't mean I support harassing women, it means I understand that there is no particular right to not be given offense.
Threats are a different ballgame. There is no excuse for threatening anyone. That, however, is not a threat. It's just a shitty person, likely a very young shitty person, saying a shitty thing.
>You're ok with that? We should just expect the target of that email to "get over it?"
Some idiotic person anonymously typed something idiotic. In that case, yes, you're best to "get over it". There are many things in the world I'm not okay with. But it's pointless to froth at the mouth over what some (likely) adolescent boy typed on the internet.
On the other hand, if someone is making real-life threats to your person, go to the police.
> "Women are the niggers of gender," the email said. "If you killed yourself, I wouldn’t even fuck the corpse."
You're ok with that? We should just expect the target of that email to "get over it?"
No.