HubSpot will automatically omit sending marketing emails to contacts who marked one of your past marketing emails as spam to protect your email sending reputation. You can remove these contacts by exporting them, reviewing the export, then importing the contacts as a static list of contacts to delete from your account.
Please note: contacts who mark your emails as spam will hurt your email sending reputation, and could lead to a suspension of your ability to send email. Make sure you're following the best practices of our email deliverability guidelines.
First, export a list of the contacts who marked one of your marketing emails as spam:
You'll receive an email with a download link to the export file, which will include a single column labelled Portal Spam Report. This column indicates whether a contact marked a marketing email from your account as spam, or they moved the email from their inbox into their junk folder. You should see a value of TRUE in this column for every contact.