Well really it's not about you emailing them and telling them about your items. Seems like they only buy the popular stuff, so if they haven't heard about your auction, it's probably not something they want anyway. They will come to you if it's something they want. Otherwise, everyone should respect their time by not filling their inbox with "hey look at this" emails, as I'm sure they get a lot of those, and it's probably annoying. Just my thoughts.
Ok, I just asked them this very question in person, and here is the official response. (It's not a direct quote, but it's the general idea.)
How to get Golden Palace to look at your item:
Create media attention for your item. When they hear about it through the media, that means a lot more than if they hear about it from you. Once the media attention is there, there is still no reason for you to contact them. If it's not big enough that they hear about it, it's not something they want. Of course there are the rare occasions when they pick off smaller auctions that have a funny sentimental value to them, but if you want to sell an item for serious money to Golden Palace, you need to first create serious media attention.