4d412336_on___SecureLine___How_it_Works__Encryption_Option
[0] 3. [Discussion] SecureLine will look in the sender's address books for pre-configured encryption information for the recipient. This could be a PGP or S/MIME public key or an Escrow Question and Answer. The first entry with encryption information found is used. User Address Books are searched in the following order: a. Preferred address book for SecureLine data, if specified b. All subscribed address books, if there are any b. Default address book, if none are subscribed [Encryption Option] 
PKI or Escrow Question and Answer from Address Book data
LuxSci - HIPAA HITECH Compliant Email Encryption - SecureLine - How it Works
Encryption Option