Kaspersky Secure Mail Gateway Email messages from Internal Server stuck in the Anti-Spam Quarantine

We’re running a POC with trial of Kaspersky Secure Mail Gateway. We’re receiving emails and they’re being routed correctly to internal mail servers.

However the external emails sent from our internal mail servers are stuck in the Anti-Spam Quarantine Message Queue.

If I flush they are delivered normally. Any clue what’s we’re doing wrong here?