Spam and Open Relay Blocking System (SORBS)

What is Spam and Open Relay Blocking System (SORBS)?

Proofpoint Inc created SORBS. The service offers senders free access to Proofpoint’s DNS-based Block List (DNSBL), which can be leveraged to block email from over 12 million host servers associated with malicious emails, phishing attacks, and spam. Despite being a low impact blocklist, many senders hit the SORBS.

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• Preference Center
• Cloudmark
• Sender Policy Framework (SPF)
• Email Filter
• SMTP
• Throttling
• Opt-Out/Unsubscribe
• Allowlist