If you are NOT using SSL Inspector, then your TLS-encrypted emails are being blocked by Spam Blocker. Go to Apps > Spam Blocker > Email > Advanced SMTP Configuration and check the option for "Allow and ignore TLS sessions". This is disabled by default. Enable this to allow TLS emails to pass.
If, after enabling that option in Spam Blocker, your TLS encrypted emails are still not passing, uninstall and reinstall Phish Blocker. Phish Blocker gets its settings from Spam Blocker when Phish Blocker is installed. If you change the settings of Spam Blocker, you will need to uninstall and reinstall Phish Blocker in order for the changes to be applied to Phish Blocker.