From d15ac1d3c1ef963ad30c4372b16094366469e0b6 Mon Sep 17 00:00:00 2001
From: timedout <git@nexy7574.co.uk>
Date: Thu, 22 Jan 2026 14:45:55 +0000
Subject: [PATCH] fix: Use 404 instead of 400 (and include sender)

---
 changelog.d/1308.feature.md | 2 ++
 src/core/error/response.rs  | 3 ++-
 2 files changed, 4 insertions(+), 1 deletion(-)
 create mode 100644 changelog.d/1308.feature.md

diff --git a/changelog.d/1308.feature.md b/changelog.d/1308.feature.md
new file mode 100644
index 00000000..467195f3
--- /dev/null
+++ b/changelog.d/1308.feature.md
@@ -0,0 +1,2 @@
+Added unstable support for [MSC4406: `M_SENDER_IGNORED`](https://github.com/matrix-org/matrix-spec-proposals/pull/4406).
+Contributed by @nex
diff --git a/src/core/error/response.rs b/src/core/error/response.rs
index f21c4c66..d1f09a99 100644
--- a/src/core/error/response.rs
+++ b/src/core/error/response.rs
@@ -85,7 +85,8 @@ pub(super) fn bad_request_code(kind: &ErrorKind) -> StatusCode {
 		| Unrecognized => StatusCode::METHOD_NOT_ALLOWED,
 
 		// 404
-		| NotFound | NotImplemented | FeatureDisabled => StatusCode::NOT_FOUND,
+		| NotFound | NotImplemented | FeatureDisabled | SenderIgnored { .. } =>
+			StatusCode::NOT_FOUND,
 
 		// 403
 		| GuestAccessForbidden