Reply #1, in response to a reply from madfilkentist:
You're wrong. I've gone into much more detail on my own LJ about why you're wrong.
Yes, I've been around the internet a while. I know about these things. I know that if I give a bid or convention my contact information, I'm telling them that they can contact me. In fact, I want them to contact me. That makes every contact from them solicited. I see nothing at all in such transactions that limits e-mail contacts to discussions of the financial purchase of the membership itself, as you obviously do. But then, I'm obviously not nearly as fannish as you are. And I wouldn't take that as a compliment if I were you.
I'll as you right here the question I asked over there: Pretend you're running a Worldcon bid. The by-mail voting deadline is so close that sending printed pieces of paper through the postal mail is too slow. How do you contact your supporters and remind them that it's time to vote? Remember that a whole bunch of your supporters really do not understand this whole voting process at all.
Reply #2, an afterthought to the first reply:
Actually, I will also pose the case that I cited on my own LJ. Assume for the sake of argument that you purchased a table in the current Worldcon's dealers' room. As part of this, you signed up for the dealers' room announcements list, where the DR coordinator sends out information about the dealer's room.
The DR coordinator then posts a message to you (and obviously, all of the other dealers) saying, "Our Worldcon has the following opportunities for advertising in our publications and at the convention. You might want to buy an ad to try and attract more people to your table. If so, see [address] to purchase advertising." By your standard, is this "spam" or not?