How should I respond to this email from a customer?

Buy a cheap one. Wrap the box in aluminum foil.

Wait about 3 weeks, incase of a second EMP, then unwrap it and plug it in.

What exactly does an EMP do to electronics that disables them? I always thought it was only digital circuits that were susceptible. I had a microwave oven and clothes dryer get fried by a power surge from a lightning bolt that hit the power line, but that went into those appliances through the wiring in the wall from the power line. It blew all the light bulbs out in the neighbor's house. Had it been just a lightning bolt within proximity and hadn't been conducted into the circuitry, everything would've been fine.

Lightning bolts actually do cause EMPs, but I've never heard of a refrigerator getting damaged by a nearby lightning strike.

I've seen all the appliances hit and fried by lightning before. It's funny that way.

isn't the solar generator going to have the same problem?

You would think

Anyone else starting out on anything less than a used microwave with two flat prongs cut, plugged into an outlet, isn't worth wasting time on...