diff --git a/src/chat/chat_tests.rs b/src/chat/chat_tests.rs
index d2539fdc3..2b1a2ea95 100644
--- a/src/chat/chat_tests.rs
+++ b/src/chat/chat_tests.rs
@@ -2495,7 +2495,9 @@ async fn test_broadcast() -> Result<()> {
     }
 
     {
-        let msg = bob.recv_msg(&alice.pop_sent_msg().await).await;
+        let sent_msg = alice.pop_sent_msg().await;
+        assert!(!sent_msg.payload.contains("Chat-Group-Member-Timestamps:"));
+        let msg = bob.recv_msg(&sent_msg).await;
         assert_eq!(msg.get_text(), "ola!");
         assert_eq!(msg.subject, "Broadcast list");
         assert!(!msg.get_showpadlock()); // avoid leaking recipients in encryption data
@@ -3536,3 +3538,12 @@ async fn test_restore_backup_after_60_days() -> Result<()> {
 
     Ok(())
 }
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_one_to_one_chat_no_group_member_timestamps() {
+    let t = TestContext::new_alice().await;
+    let chat = t.create_chat_with_contact("bob", "bob@example.com").await;
+    let sent = t.send_text(chat.id, "Hi!").await;
+    let payload = sent.payload;
+    assert!(!payload.contains("Chat-Group-Member-Timestamps:"));
+}
diff --git a/src/mimefactory.rs b/src/mimefactory.rs
index 5b65e5c88..9bb9bc73d 100644
--- a/src/mimefactory.rs
+++ b/src/mimefactory.rs
@@ -622,24 +622,23 @@ impl MimeFactory {
             );
         }
 
-        let chat_memberlist_is_stale = if let Loaded::Message { chat, .. } = &self.loaded {
-            chat.member_list_is_stale(context).await?
-        } else {
-            false
-        };
-
-        if !self.member_timestamps.is_empty() && !chat_memberlist_is_stale {
-            headers.push(
-                Header::new_with_value(
-                    "Chat-Group-Member-Timestamps".into(),
-                    self.member_timestamps
-                        .iter()
-                        .map(|ts| ts.to_string())
-                        .collect::<Vec<String>>()
-                        .join(" "),
-                )
-                .unwrap(),
-            );
+        if let Loaded::Message { chat, .. } = &self.loaded {
+            if chat.typ == Chattype::Group
+                && !self.member_timestamps.is_empty()
+                && !chat.member_list_is_stale(context).await?
+            {
+                headers.push(
+                    Header::new_with_value(
+                        "Chat-Group-Member-Timestamps".into(),
+                        self.member_timestamps
+                            .iter()
+                            .map(|ts| ts.to_string())
+                            .collect::<Vec<String>>()
+                            .join(" "),
+                    )
+                    .unwrap(),
+                );
+            }
         }
 
         let subject_str = self.subject_str(context).await?;