Hi Adam
If you look into your MPL log in HCI, you can see that the error is happening when trying to send the message to the receiver COD system.
Processing exchange ID-vsa697905-od-sap-biz-33144-1448124847088-5-22 in cxf:bean:COD_{
Error = org.apache.cxf.interceptor.Fault: Could not generate the XML stream caused by: javax.xml.stream.XMLStreamException: javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target., cause: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
SSL handshake with the target system failed because the certificate for the target system is not in your HCI tenant keystore.
To do that you need to update the system.jks keystore in your tenant with the root CA certificate for the C4C site. Refer to Paul's blog below for a comprehensive step by step guide on how to do it with the help of Keystore Explorer. I'd normally just import the Root CA (and not the whole chain of certificate)
HCI First Steps Part 8 - Working with Certificates
After you have updated the keystore in HCI, you can test it out using the Test Outbound Connection feature in the Node Explorer.
Rgds
Eng Swee