dear all, recently i heard some conversation between a client and a sales man

sales man are selling his email marketing service. He said his service will help the client to send 10K to 20K mail/newsletter to the client's customer.

and the client ask whether the customer receive the news letter as spam mail, since one short send so many out.

i have few question here

1. the sales man promise it won drop as spam to the customer mail box. Why, any special server or IP they use?

2. If we do it our self, (own email) it sure get in to spam section at the customer mail box... some more can get black listed in those spam directory website(i dono what this website call) is some thing like the askimet in our wordpress plugin agent.

so which is this website, any one know can list out this kind of spam mail directory?