I understood that these email addresses exist.
Quarantining, black-hole bounces, being caught in a firewall/“enterprise spam filter”, and spam folder placement are all generally symptoms of the same root issue… graymail, or a low overall open rate.
Your marketing/sales email has a different reputation than whatever system you use for direct emails, and if for some reason that reputation has issues the first thing you are going to want to do is remove historically low engaged contacts. Otherwise, your ability to deliver to the engaged may be compromised.