PGP Universal Server fails to send encrypted emails to external users because the external user's public key is not found.
The solution to this issue is to configure PGP Universal Server to search for public keys of external users on the PGP Key Server.
This can be achieved by following these steps:
This will allow PGP Universal Server to search for keys with the email address in the external users key server. If the keys is found then it will send the email encrypted. PGP Universal Server can also search for keys in the PGP Global Directory. To do so, please follow the link below:
http://www.symantec.com/docs/HOWTO59090