What is SURBL and how does it differ from Spamhaus?

SURBL:

• URI blocklist (domains in content)
• Lists domains appearing in spam
• Focuses on links and advertised sites
• Does not list sending IPs

Spamhaus SBL/XBL:

• IP blocklists
• Lists sending IP addresses
• Focuses on spam senders

Spamhaus DBL:

• Domain blocklist (similar to SURBL)
• Lists domains in spam content

Combined impact:

• Your IP can be clean but domain listed
• Or domain clean but IP listed
• Check both types
• Different blocklist types catch different abuse patterns.

Ship registration versus cargo origin. Different registries track different things.