We are trying to get an Outbound Message to an SAP Endpoint URL.

So after double checking the Certificates. It seems that the Root Certificate on the Endpoint is a valid Salesforce.com CA:
Issuer: CN=VeriSign Class 3 Public Primary Certification Authority - G5, OU="(c) 2006 VeriSign, Inc. - For authorized use only", OU=VeriSign Trust Network, O="V eriSign, Inc.", C=US

There is an Intermediary Certificate that does have the Root CA Authority (ISSUER) and the OWNER in this cert is on the SSL Certificate

Owner: CN=Symantec Class 3 Secure Server CA - G4, OU=Symantec Trust Network, O=Symantec Corporation, C=US
Issuer: CN=VeriSign Class 3 Public Primary Certification Authority - G5, OU="(c) 2006 VeriSign, Inc. - For authorized use only", OU=VeriSign Trust Network, O="VeriSign, Inc.", C=US

And the SSL Certificate for the Endpoint (OWNER) does point to the Intermediate Certificate (ISSUER) CA Authority

Owner: CN=hds-solmandev.hdsmith.com, OU=solman, O="H.D Smith, LLC", L=Springfiel
d, ST=Illinois, C=US
Issuer: CN=Symantec Class 3 Secure Server CA - G4, OU=Symantec Trust Network, O=
Symantec Corporation, C=US

Will this be enough to send an outbound message to the Endpoint URL? It keeps failing with the error: javax.net.ssl.SSLPeerUnverifiedException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

The port is also open from Salesforce to the Endpoint URL