What is SURBL and how does it differ from Spamhaus?

SURBL versus 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.