From ec4d195814c7d27a77c1a15f3a8d8618b140aa4e Mon Sep 17 00:00:00 2001
From: link2xt <link2xt@testrun.org>
Date: Thu, 13 Aug 2026 09:14:48 +0000
Subject: [PATCH] fix: send MDNs to self even if MDNs are disabled

MDNs to self are used for seen status synhronization between devices.
---
 .../tests/test_multidevice.py                 | 31 +++++++++++++++++++
 src/config.rs                                 |  3 ++
 src/smtp.rs                                   |  6 ----
 3 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/deltachat-rpc-client/tests/test_multidevice.py b/deltachat-rpc-client/tests/test_multidevice.py
index 3cec49bd3..8ae9c7ca3 100644
--- a/deltachat-rpc-client/tests/test_multidevice.py
+++ b/deltachat-rpc-client/tests/test_multidevice.py
@@ -127,3 +127,34 @@ def test_multidevice_sync_seen(acfactory, log):
     assert ac1_clone_message.get_snapshot().state == MessageState.IN_SEEN
     # Test that the timer is started on the second device after synchronizing the seen status.
     assert "Expires: " in ac1_clone_message.get_info()
+
+
+def test_multidevice_sync_seen_mdns_off(acfactory, log):
+    """Test that MDNs to self are sent even if MDNs are disabled."""
+    ac1, ac2 = acfactory.get_online_accounts(2)
+    ac1.set_config("mdns_enabled", "0")
+
+    ac1_clone = ac1.clone()
+    ac1_clone.bring_online()
+
+    assert ac1.get_config("bcc_self") == "1"
+    assert ac1.get_config("mdns_enabled") == "0"
+    assert ac1_clone.get_config("bcc_self") == "1"
+    assert ac1_clone.get_config("mdns_enabled") == "0"
+
+    ac1.create_chat(ac2)
+    ac1_clone_chat = ac1_clone.create_chat(ac2)
+    ac2_chat = ac2.create_chat(ac1)
+
+    log.section("Send a message from ac2 to ac1 and check that it's 'fresh'")
+    ac2_chat.send_text("Hi")
+    ac1_message = ac1.wait_for_incoming_msg()
+    ac1_clone_message = ac1_clone.wait_for_incoming_msg()
+
+    ac1_message.mark_seen()
+    assert ac1_message.get_snapshot().state == MessageState.IN_SEEN
+
+    log.section("ac1 clone detects that message is marked as seen")
+    ev = ac1_clone.wait_for_event(EventType.MSGS_NOTICED)
+    assert ev.chat_id == ac1_clone_chat.id
+    assert ac1_clone_message.get_snapshot().state == MessageState.IN_SEEN
diff --git a/src/config.rs b/src/config.rs
index eec88cd73..779b3b50b 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -177,6 +177,9 @@ pub enum Config {
 
     /// True if Message Delivery Notifications (read receipts) should
     /// be sent and requested.
+    ///
+    /// MDNs to self used for seen status synchronization between devices
+    /// are sent in any case when multi-device mode (bcc_self) is enabled.
     #[strum(props(default = "1"))]
     MdnsEnabled,
 
diff --git a/src/smtp.rs b/src/smtp.rs
index 0655c761a..28ecb0fc6 100644
--- a/src/smtp.rs
+++ b/src/smtp.rs
@@ -649,12 +649,6 @@ async fn send_mdn_rfc724_mid(
 
 /// Tries to send a single MDN. Returns true if more MDNs should be sent.
 async fn send_mdn(context: &Context, smtp: &mut Smtp) -> Result<bool> {
-    if !context.should_send_mdns().await? {
-        context.sql.execute("DELETE FROM smtp_mdns", []).await?;
-        return Ok(false);
-    }
-    info!(context, "Sending MDNs.");
-
     context
         .sql
         .execute("DELETE FROM smtp_mdns WHERE retries > 6", [])