1 files changed, 13 insertions, 0 deletions
diff --git a/docs/usage/configuration/config_documentation.md b/docs/usage/configuration/config_documentation.md
index 282b59dec9..f51924f064 100644
--- a/docs/usage/configuration/config_documentation.md
+++ b/docs/usage/configuration/config_documentation.md
@@ -761,6 +761,19 @@ email:
     password_reset: "[%(server_name)s] Password reset"
     email_validation: "[%(server_name)s] Validate your email"
 ```
+---
+### `max_event_delay_duration`
+
+The maximum allowed duration by which sent events can be delayed, as per
+[MSC4140](https://github.com/matrix-org/matrix-spec-proposals/pull/4140).
+Must be a positive value if set.
+
+Defaults to no duration (`null`), which disallows sending delayed events.
+
+Example configuration:
+```yaml
+max_event_delay_duration: 24h
+```
 
 ## Homeserver blocking
 Useful options for Synapse admins.