spam vs. email ads

[WrigleyF]

When does an email become spam? Are all unwanted emails spam? If I send out a legitimate email ad to people I don't know, is that spamming, or is it only spam if they asked me not to send them anymore ads and I kept doing it anyway?

[rich]

Is the mailing list you have legit? Did these people opt-in to receive ads/promotions from you?