If you open Encryption Desktop and right click on a PGP key you will find the option Send To / Symantec Encryption Server:
This option does not allow the user to upload a third party's public key to Encryption Management Server.
Symantec Encryption Desktop 10.3.2 MP13 and above, Encryption Management Server 3.3.2 MP13 and above.
The Send To / Symantec Encryption Server option only allows users who are not using SKM key mode to upload a copy of their private key to Encryption Management Server. This may be necessary after the user changes the properties of their key.
If you wish to allow users to upload third party public keys to Encryption Management Server, you will need to enable Encryption Management Server Verified Directory.