What I just entered into the customer service comment form on Netflix:

Can’t you get your marketing partners to quit spamming me about your service? You know I have an account, there’s no reason to send me the average of FIVE MESSAGES PER DAY which ask me to sign up. Even if I weren’t a member, I’d NEVER sign up for this service through unsolicited mail, and if I’d gotten this level of mail from them (read: you) before I was a member I never would have signed up (“wow, they must be jerks”). If it gets much worse I’ll probably discontinue the service so I can safely filter and delete any mail containing the word ‘netflix’.

Pressing “send” resulted in an error, twice in a row, so who knows whether it got through.