Google Message Encryption Administration Guide - Manual (Page 25)

26 Postini Encryption Services Administration Guide
You will also need to enable Transport Layer Security (TLS) on your mail server.
Setting up TLS on your server ensures that your confidential email is secure
throughout transmission. For information on implementing TLS on your mail
server, check your mail server documentation. If you are using multiple servers,
enable TLS on each server that routes mail to the email protection service, and
configure TLS in the Administration Console.
Billing
Billing for Message Encryption is based on the number of users that have
Message Encryption enabled in the Administration Console.
Any user with individual Message Encryption enabled, or inside an organization
with org-level Message Encryption enable, is billed. This includes users that don’t
actively use Message Encryption.
For details about pricing and other billing questions, contact your sales
representative.
How Portal Delivery Works
You can also set Portal Delivery for a specific org or user. You can set Portal
Delivery to send all outbound mail securely, or only messages that have been
marked for encryption. With Portal Delivery, outbound mail is first routed to the
email protection service, then to the Secure Portal. In the Secure Portal, the
recipient can securely read, download, and reply to the message. Portal Delivery
then sends the recipient a notification that a message has arrived, which includes
a link to the Secure Portal.