If you wouldn't want someone marketing to you in a certain way, don't do it to other people. You'll be a better company, a better marketer mailing list and a better person for it. In what way would you send your business e-mails to individuals you do not know, but are prepared to receive such e-mail from you? Wait, that does not look true. How could this happen? If you know what's really happening, it is actually rather simple.
This is way possible by being a member of safe list. Each one who is listed on the safe lists, knows that they will be getting emails from different members. This is probable because that is one of the conditions of their "safe list" membership. Thus those who sign up to these lists are willing to say yes to this requirement for the reason that they themselves would want to send out their own business electronic mails to the others on the list.