diff --git a/tsp/src/async_store.rs b/tsp/src/async_store.rs
index 281fa2f..7af575c 100644
--- a/tsp/src/async_store.rs
+++ b/tsp/src/async_store.rs
@@ -369,18 +369,15 @@ impl AsyncStore {
             let db_inner = db.clone();
             async move {
                 match message {
-                    Ok(mut m) => {
-                        let m_copy = m.clone();
-                        match db_inner.open_message(&mut m) {
-                            Err(Error::UnverifiedSource(unknown_vid)) => {
-                                Ok(ReceivedTspMessage::PendingMessage {
-                                    unknown_vid,
-                                    payload: m_copy,
-                                })
-                            }
-                            maybe_message => maybe_message.map(|msg| msg.into_owned()),
+                    Ok(mut m) => match db_inner.open_message(&mut m) {
+                        Err(Error::UnverifiedSource(unknown_vid, opaque_data)) => {
+                            Ok(ReceivedTspMessage::PendingMessage {
+                                unknown_vid,
+                                payload: opaque_data.unwrap_or(m),
+                            })
                         }
-                    }
+                        maybe_message => maybe_message.map(|msg| msg.into_owned()),
+                    },
                     Err(e) => Err(e.into()),
                 }
             }
diff --git a/tsp/src/error.rs b/tsp/src/error.rs
index 70b6feb..0157207 100644
--- a/tsp/src/error.rs
+++ b/tsp/src/error.rs
@@ -32,7 +32,7 @@ pub enum Error {
     #[error("Error: unresolved vid {0}")]
     UnverifiedVid(String),
     #[error("Error: no relation with sender {0}")]
-    UnverifiedSource(String),
+    UnverifiedSource(String, Option<Vec<u8>>),
     #[error("Error: unresolved next hop {0}")]
     UnresolvedNextHop(String),
     #[error("Error: no relation with next hop {0}")]
diff --git a/tsp/src/store.rs b/tsp/src/store.rs
index 63b44db..25788e6 100644
--- a/tsp/src/store.rs
+++ b/tsp/src/store.rs
@@ -514,6 +514,14 @@ impl Store {
         }
     }
 
+    /// Get the sender from a CESR message
+    fn probe_sender(message: &mut [u8]) -> Result<&str, Error> {
+        Ok(match crate::cesr::probe(message)? {
+            EnvelopeType::EncryptedMessage { sender, .. } => std::str::from_utf8(sender)?,
+            EnvelopeType::SignedMessage { sender, .. } => std::str::from_utf8(sender)?,
+        })
+    }
+
     /// Decode an encrypted `message``, which has to be addressed to one of the VIDs in `receivers`, and has to have
     /// `verified_vids` as one of the senders.
     pub fn open_message<'a>(
@@ -536,7 +544,7 @@ impl Store {
                 let sender = String::from_utf8(sender.to_vec())?;
 
                 let Ok(sender_vid) = self.get_verified_vid(&sender) else {
-                    return Err(Error::UnverifiedSource(sender));
+                    return Err(Error::UnverifiedSource(sender, None));
                 };
 
                 let (nonconfidential_data, payload) =
@@ -550,7 +558,19 @@ impl Store {
                         message_type: MessageType::SignedAndEncrypted,
                     }),
                     Payload::NestedMessage(inner) => {
+                        // we must communicate the correct payload to the caller, in case
+                        // the inner vid isn't recognized (which can happen in Routed mode)
+                        // we cannot do this after 'open_message' since 'inner' will be borrowed
+                        let inner_vid = Self::probe_sender(inner)?;
+                        if self.get_verified_vid(inner_vid).is_err() {
+                            return Err(Error::UnverifiedSource(
+                                inner_vid.to_owned(),
+                                Some(inner.to_vec()),
+                            ));
+                        }
+
                         let mut received_message = self.open_message(inner)?;
+
                         if let ReceivedTspMessage::GenericMessage {
                             ref mut message_type,
                             ..