Email Test Connect fails with SMTP errors PKIX path validation failed (4379811)

Moved from Stat 6.3 to Stat 7.0, the SMTP Test connection fails with Email Test Connect fails with SMTP errors below:

PKIX path validation failed: java.security.cert.CertPathValidatorException: Algorithm constraints check failed on keysize limits: RSA 2048-bit key.

The system's cryptographic policies have disabled RSA public keys with 2048 size.

It should be investigated further, and look into the crypto policies file of that particular machine.

The real cause is in the /etc/crypto-policies of the OS, in particular Fedora/RHEL. Refer to the article here. 

Solution:

Edit app/standalone/configuration/stat.java.security.properties file, adding the line below:

security.useSystemPropertiesFile=false

Bounce the SCA after deleting the cache directories (data, log, and tmp).