Did you know that sending out mass emails is often illegal? You perhaps didn't. Particularly if you work as a politics blogger, for which an important part of your job is "blasting out" your stories.
But the deeply flawed CAN-SPAM Act of 2003 codified some mass email behavior, and described what's spam and what isn't. The FTC describes what emails are subject to the Act: "'any electronic mail message the primary purpose of which is the commercial advertisement or promotion of a commercial product or service,' including email that promotes content on commercial websites."
So, yes. Your mass email promoting your "content" at Politico or BuzzFeeᴅ or your Tumblr or your mom's Facebook is considered spam, if it does not include a real mailing address for the sender in the body of the email, or if it doesn't explain how to opt out from the email list that the recipient hasn't chosen to be on.