Cisco Cisco Email Security Appliance C670 ユーザーガイド

Click Advanced under Key Server Settings to specify whether to use HTTP or HTTPS for transfering 
the envelope’s encrypted payload when the recipient opens the envelope. You can from one of the 
following:

Use the Key Service with HTTP. Transfers the encrpyted payload from the key service using HTTP 
when the recipient opens the envelope. If you are using Cisco Registered Envelope Service, this is 
the URL you specified in 

. If you are using the Cisco IronPort Encryption appliance, this is 

the external URL you specified in 

Since the payload is already encrypted, transporting it over HTTP is safe and faster than sending 
over HTTPS. This provides better performance than sending image requests over HTTPS.

Use the Key Service with HTTPS. Transfers the encrpyted payload from the key service using 
HTTPS when the recipient opens the envelope. If you are using Cisco Registered Envelope Service, 
this is the URL you specified in 

. If you are using the Cisco IronPort Encryption appliance, 

this is the external URL you specified in 

Specify a separate URL for payload transport. If you don’t want to use the key server for your 
encrypted payload, you can use another URL and specify whether to use HTTP or HTTPS for the 
payload transfer.

In the Envelope Settings section, select the level of message security:

High Security. The recipient must always enter a password to open encrypted messages.

Medium Security. The recipient does not need to enter credentials to open the encrypted message 
if the recipient credentials are cached.

No Password Required. This is the lowest level of encrypted message security. The recipient does 
not need to enter a password to open the encrypted message, but the read receipts, Secure Reply, 
Secure Reply All, and Secure Message Forwarding features will be unavailable to prevent another 
email user from sending a message on behalf of the original recipient. 

To enable users to open your organization’s URL by clicking its logo, you can add a link to the logo. 
Choose from the following options:

No link. A live link is not added to the message envelope.

Custom link URL. Enter the URL to add a live link to the message envelope. 

Optionally, enable read receipts. If you enable this option, the sender receives a receipt when recipients 
open the secure envelope.

Optionally, click Advanced under Envelope Settings to configure the following settings:

Enter the length of time (in seconds) that a message can be in the encryption queue before timing 
out. Once a message times out, the appliance bounces the message and sends a notification to the 
sender.

Select an encryption algorithm:

ARC4. ARC4 is the most common choice, providing strong encryption with minimal 
decryption delays for message recipients.

AES. AES provides stronger encryption but also takes longer to decrypt, introducing delays for 
recipients. AES is typically used in government and banking applications.

Enable or disable the decryption applet. Enabling this option causes the message attachment to be 
opened in the browser environment. Disabling this option causes message attachments to be 
decrypted at the key server. If you disable this option, messages may take longer to open, but are not 
dependent on the browser environment.

In the Message Settings section, enable or disable Secure Reply All.

Enable or disable Secure Message Forwarding.