What’s the difference between a reputation list and a blocklist?

A blocklist provides a binary answer: an IP or domain is either listed or not. There is no middle ground. Being listed typically triggers negative consequences.

A reputation list or reputation service provides graduated scores. Rather than yes or no, you receive a rating that indicates where you fall on a spectrum from very bad to very good.

Sender Score from Validity is a reputation service that rates senders from 0 to 100. Google Postmaster Tools shows reputation categories (bad, low, medium, high). These provide nuanced information beyond simple listing status.

Reputation affects how filters treat your mail. A low reputation adds friction; a high reputation provides latitude. Blocklisting is more absolute, often triggering outright rejection.

A blocklist says stop or go. A reputation list says how fast you can sail through inspection.