From b859ae589b740f41ba41dab1e4bb003225db3478 Mon Sep 17 00:00:00 2001
From: Thomas <31560900+0xtlt@users.noreply.github.com>
Date: Wed, 14 Dec 2022 09:18:52 +0100
Subject: [PATCH] Update 40.md

---
 40.md | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/40.md b/40.md
index 232da49..8aa9538 100644
--- a/40.md
+++ b/40.md
@@ -41,6 +41,12 @@ Clients SHOULD use the `supported_nips` field to learn if a relay supports this
 
 Clients MUST ignore events that have expired.
 
+Relay Behavior
+--------------
+
+Relays SHOULD NOT delete an expired message immediately on expiration. Relays that wish to purge expired messages from their DB should allow for a grace period before deletion. For example, this could be 24h after event expiration.
+Relays MAY choose to not delete expired messages.
+
 Suggested Use Cases
 -------------------