Two of the biggest spammers in the world are Salesforce and Hubspot. They should both be blacklisted yet most of their email goes into the inbox.

Considering I get spam from large U.S. companies because they believed someone else when they used my email to sign up for something, I am inclined to agree with you. No matter how many times I click "mark as spam" in Gmail, it always gets delivered to my inbox.

Credit Karma is the biggest offender off the top of my head. For a company in the consumer datamining business, they sure aren't doing a good job.