It would be impossible to write a book about email marketing without talking about spam.
There are various laws covering spam around the world. For a complete overview of the spam laws in your territory visit: en.wikipedia.org/wiki/Email_spam. However, despite the slight differences in anti-spam legislation around the globe there is only one real definition for spam.
Spam is unsolicited commercial email. Make no mistake, it is loathed in equal measure by the people it targets and virtually everyone who works in the email marketing industry. Anyone who works in the email marketing industry who encourages the use of spam is not to be trusted. Spam damages reputations and in many cases is illegal. You don’t want to be a spammer.