Using email accounts to connect to an email server using self-signed keys and requiring TLS can fail on the TLS handshake.
Steps to Reproduce
Go to /sys_properties_list.do and set com.glide.communications.trustmanager_trust_all to true.
Upload the target email system certificates to be used when using TLS.
For more information, see the product documentation topic Basic email setup.
Upgrade your instance to Java 1.8+.
If the problem persists, get the target email system certificates signed by a valid Certificate Authority (CA).
Related Problem: PRB667334