<Snipped quote by Willy Vereb>
Well, energy shielding is just that, meant to absorb energy, I believe since we don't exactly have true science on this yet. Unless if we're say, a plasma shield, then I think it would be able to negate an EMP missile. As for materials, the EMP just needs to get past the hull unless the entirety of the ship is made of that once substance, not all substances have these kinds of effects against EMP.
Edit: don't quote me on any of this, I'm just relaying what I have learned over the years.
EMP is basically an AoE DEW. Aside from interfering with a spacecraft's sensory equipment for a brief period of time, it's not going to really do much damage (if any at all) to a properly-engineered spacecraft. It's to be assumed that the generality of the spaceships zipping about in this RP are going to be sufficiently proofed against stellar radiation elements (star flares, cosmic rays, ect) and--at least for military-grade starships--heavily resistant to mainstream DEWs that can wreck untold havoc on improperly shielded electronics (in example: particle beam weapons, electrolasers, x-ray lasers, and gamma ray lasers).
They're not useless weapons, but they'd be more effective against civilian targets.
Though, a spacefaring (or non-spacefaring) civilization that's still running mechanical computing technology and vacuum tubes or a nation that has forsaken silicon-based electronic technology in favor of optical fiber cabling and laser-based wireless energy transfer methods is probably going to snub an EMP attack with comparatively little effort.
But that's hard science bullshit. No one wants the fun sucked out of this game with nonsense like that.
EDIT: Wow, this filled up quick.