diff --git a/README.md b/README.md
index 637de63..caceaf9 100644
--- a/README.md
+++ b/README.md
@@ -49,6 +49,19 @@ Defaults: `overall=70`, `dns=70`, `authentication=80`, `spam=70`,
 `blacklist=90`, `header=70`, `content=60`. Each can be customised through
 the rule options shown in the happyDomain UI.
 
+## Rules
+
+| Code                                  | Description                                                                                       | Severity |
+|---------------------------------------|---------------------------------------------------------------------------------------------------|----------|
+| `happydeliver.score.overall`          | Verifies happyDeliver's Overall score is above the configured minimum.                            | CRITICAL |
+| `happydeliver.score.dns`              | Verifies happyDeliver's DNS score is above the configured minimum.                                | CRITICAL |
+| `happydeliver.score.authentication`   | Verifies happyDeliver's Authentication (SPF/DKIM/DMARC) score is above the configured minimum.    | CRITICAL |
+| `happydeliver.score.spam`             | Verifies happyDeliver's Spam filters score is above the configured minimum.                       | CRITICAL |
+| `happydeliver.score.blacklist`        | Verifies happyDeliver's Blacklists score is above the configured minimum.                         | CRITICAL |
+| `happydeliver.score.header`           | Verifies happyDeliver's Headers score is above the configured minimum.                            | CRITICAL |
+| `happydeliver.score.content`          | Verifies happyDeliver's Content score is above the configured minimum.                            | CRITICAL |
+| `happydeliver.lifecycle`              | Reports happyDeliver lifecycle errors (allocation, send, timeout, fetch).                         | CRITICAL |
+
 ## Metrics
 
 One `happydeliver_score` metric per section, labelled with `section=<name>`