Firewalls can significantly impact email deliverability: - Blocking Suspicious Emails: Firewalls can block emails that appear suspicious or come from untrusted sources, which helps in maintaining the integrity of your email list. - Filtering Spam: Modern firewalls often include spam filters that help in reducing the likelihood of your emails being marked as spam. This is crucial for maintaining a good sender reputation. - Ensuring Compliance: Firewalls help in ensuring compliance with anti-spam laws and guidelines, which is important for maintaining high deliverability rates.