The actual definition of spam is unsolicited (usually) commercial messages via email, text messages, or mail, sent to a large number of recipients.
Spam emails are also known as junk email, and unsolicited messages sent in bulk are referred to as “spamming”. Many countries like have spam guidelines (CASL – Canada’s Anti-Spam Legislation, US FTC CAN-SPAM Act, European Union Spam Rules), and you can report companies for sending you unsolicited mail, which may result in a fine, and/or blacklisting for the company at fault. All of these rules and laws force companies to ensure that the persons being mailed have “opted in” or “subscribed” to receive the mail and that each email contain a visible “opt out” or “unsubscribe”.
In the US at least one person has been able to successfully sue a company for spamming. So companies beware!