fix: Keep tombstones for two days before deleting (#3685)

This is a way to prevent redownloading locally deleted messages. Otherwise if a message is deleted
quickly after sending and `bcc_self` is configured, the BCC copy is downloaded and appears as a new
message as it happens for messages sent from another device.

src/sql.rs

@@ -990,16 +990,19 @@ async fn maybe_add_from_param(
     Ok(())
 }
 
-/// Removes from the database locally deleted messages that also don't
+/// Removes from the database stale locally deleted messages that also don't
 /// have a server UID.
 async fn prune_tombstones(sql: &Sql) -> Result<()> {
+    // Keep tombstones for the last two days to prevent redownloading locally deleted messages.
+    let timestamp_max = time().saturating_sub(2 * 24 * 3600);
     sql.execute(
         "DELETE FROM msgs
          WHERE chat_id=?
+         AND timestamp<=?
          AND NOT EXISTS (
          SELECT * FROM imap WHERE msgs.rfc724_mid=rfc724_mid AND target!=''
          )",
-        (DC_CHAT_ID_TRASH,),
+        (DC_CHAT_ID_TRASH, timestamp_max),
     )
     .await?;
     Ok(())