A SaaS-Based Email Service Provider Often Receives Reports from Legitimate

A SaaS-based email service provider often receives reports from legitimate customers that their IP netblocks are on blacklists and they cannot send email. The SaaS has confirmed that affected customers typically have IP addresses within broader network ranges and some abusive customers within the same IP ranges may have performed spam campaigns. Which of the following actions should the SaaS provider perform to minimize legitimate customer impact?

A) Inform the customer that the service provider does not have any control over third-party blacklist entries. The customer should reach out to the blacklist operator directly
B) Perform a takedown of any customer accounts that have entries on email blacklists because this is a strong indicator of hostile behavior
C) Work with the legal department and threaten legal action against the blacklist operator if the netblocks are not removed because this is affecting legitimate traffic
D) Establish relationship with a blacklist operators so broad entries can be replaced with more granular entries and incorrect entries can be quickly pruned