Obviously, there is a sufficiently large market to support spam, because otherwise they'd have to find something else to do to pay the bills. Therefore, individual effort is futile because by resisting the purchase you merely put one person of millions into the "no sale" column.
The alternative is to organize, politically or culturally. Political organizing to pass laws to regulate spam would at least be symbolically successful, even if legislation failed to produce reasonable enforcement. Cultural organizing, such as networking or boycotting might work, but is substantially more difficult, because nonparticipants are the problem and they won't necessarily want to sign up with you.
The part that makes me angry is the general application of the "vote with your dollars" principle that is used to ridicule boycotts, government regulation, and unions all in the same breath. The invisible hand, some ideologues would claim, regulates all aspects of the market. Therefore, you can individually vote with your dollars and successfully ensure living wages, a clean environment, and good healthcare by shopping at stores and buying brands who practice these things well. Ha!
Obviously, the disconnect between public opinion on these issues (vast support for) and the lack of actual success might suggest that the free market needs a tweak. But heaven forbid we use government (damn bureaucrats), consumer organizing (silly and ineffective), or union organizing (messing with the free labor market) to accomplish any of these. No, the market must reign supreme, even if it utterly fails to produce great wealth while protecting things we value. Damn the economic libertarians.