fix: do not send sync messages if bcc_self is disabled

src/config.rs

@@ -493,6 +493,14 @@ impl Context {
                 .is_some())
     }
 
+    /// Returns true if sync messages should be sent.
+    ///
+    /// This requires that both `SyncMsgs` and `BccSelf` settings are enabled.
+    pub(crate) async fn should_send_sync_msgs(&self) -> Result<bool> {
+        Ok(self.get_config_bool(Config::SyncMsgs).await?
+            && self.get_config_bool(Config::BccSelf).await?)
+    }
+
     /// Gets configured "delete_server_after" value.
     ///
     /// `None` means never delete the message, `Some(0)` means delete