diff --git a/docs/configuration.md b/docs/configuration.md
index fcadfdb1..b5bc69f5 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -194,6 +194,10 @@ matchers:
 
 # How long to wait before sending a notification again if it has already
 # been sent successfully for an alert. (Usually ~3h or more).
+# Note that this parameter is implicitly bound by Alertmanager's
+# `--data.retention` configuration flag. Notifications will be resent after either
+# repeat_interval or the data retention period have passed, whichever
+# occurs first.
 [ repeat_interval: <duration> | default = 4h ]
 
 # Times when the route should be muted. These must match the name of a