Campaign Monitor says:

“Forget any legal mumbo jumbo – here is our definition of spam.

While the CAN-SPAM laws are a step in the right direction for classifying and reducing spam, we don’t feel they go far enough. Our definition of spam goes beyond the laws in most countries and encompasses what we believe to be true permission email marketing.

Spam is any email you send to someone who hasn’t given you their direct permission to contact them on the topic of the email.

But that’s not enough. Permission is a fuzzy word open to interpretation. Let’s get into some specific scenarios so it’s clear what does and doesn’t constitute permission.

Scenarios that DON’T equate to permission:

• You obtained the email addresses from a third party
  Whether you purchased a list, were provided one by a partner or bought a bankrupt competitor’s customer list, those people never gave YOU permission to email them and they will consider your email spam. No matter the claims of the source of this list, you cannot email them.
• You have access to this list as a member of an organization or club
  Although we know that Chambers of Commerce and Tradeshow lists, for example, often give access to lists with email addresses to each member, we don’t consider this enough permission to use with our service, since the permission was not given directly to you. (If you are the organization owner and are contacting them regarding the organization, that’s ok)
• You scraped or “copy and pasted” the addresses from the Internet
  Just because people publish their email address doesn’t mean they want to hear from you.
• You haven’t emailed that address for more than 2 years
  Permission doesn’t age well. Even if you got their permission legitimately, they won’t remember giving it to you. If you haven’t sent something to that address in the last 2 years, you can’t start now.”