What is the difference between Spam and Opt-in Email?

Customer-submitted messages help us to improve our spam models by providing us access to a wide variety of spam and valid mail data. Sometimes, customers are not certain whether a particular message is spam or valid mail. Also, spam messages are sometimes accidentally submitted as valid mail or vice versa. Here is a description of different types of mail and our classification of them (spam or valid).

What is spam?

Another term for spam is unsolicited commercial/bulk email. This is a reasonable description of at least some of the e-mail that we define as spam. It may not be apparent to the recipient how the sender got their address, and it may seem like spam. But not all unwanted mail is spam.

Spam messages are unsolicited: that is, you did not agree to receive them. If you agreed to receive a message, it is not spam. Not opting out does not constitute agreement to receive bulk commercial e-mail. In order to agree to receive bulk messages, you have to opt in. Opting in (as opposed to opting out) means that you actively agreed to receive messages.

When people sign up for an email list, there is usually legal fine print. This fine print often states that the subscriber is giving the site permission to send commercial email and/or to give the email address to the third party partners. This is the business model of those web sites – they provide a free service in return for being allowed to send advertising. The recipient might not want these mails, but if they agree to the terms of service, the mail is legitimate.

Some spam messages are commercial. However, not all spam messages are ads. Scams such as advance fee fraud (419) and phish messages are not strictly commercial: the sender is not trying to sell something but rather is trying to defraud the recipient.

Also, spam messages are sent in bulk. The profile of a spam message is one or few senders, many recipients. By this definition, an unsolicited message could qualify as “not spam”. For example,
an unsolicited resume sent by an eager job-seeker does not qualify as spam, unless it was sent using spamming techniques (broadcast to a large number of recipients). Similarly, a grass-roots political campaign does not qualify as spam because it does not fit this profile, even if it uses a boilerplate and is mediated by a common website and mailserver. Rather, a message like this has many senders, few recipients.

Further reading:

Report spam from Email Logs

Limits sending or receiving email