Blocklists - Overview

What is an email blocklist (blacklist)? How do blocklists work? What are the major email blocklists (e.g., Spamhaus, Spamcop, Barracuda, SORBS)? How do I find out if my IP or domain is on a blocklist? What causes an IP/domain to get listed? How do I request removal from a blocklist? Does being on one blocklist affect my reputation everywhere? What are the main types (IP, domain, URI)? What’s the difference between blocklist and spam filter? What’s the difference between DNSBL and RBL? Who maintains blocklists (Spamhaus, Barracuda, etc.)? How are IPs or domains added to blocklists? How are listings propagated between services? What’s the difference between a public vs private blocklist? What’s the difference between a reputation list and a blocklist? How does delisting work? What are spamtraps and how do they cause blocklisting? What’s the difference between pristine and recycled spamtraps? What are typotraps or honeytraps? What’s the relationship between Spamhaus and major ISPs? How can one list affect multiple ESPs?