Cisco Cisco Email Security Appliance C170 Guia Do Utilizador
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Cisco IronPort AsyncOS 7.5 for Email Configuration Guide
OL-25136-01
Chapter 12 Cisco IronPortEmail Encryption
Using a TLS Connection as an Alternative to Encryption
Based on the destination controls specified for a domain, your Cisco IronPort
appliance can securely relay a message over a TLS connection instead of
encrypting it, if a TLS connection is available. The appliance decides whether to
encrypt the message or send it over a TLS connection based on the TLS setting in
the destination controls (Required, Preferred, or None) and the action defined in
the encryption content filter.
appliance can securely relay a message over a TLS connection instead of
encrypting it, if a TLS connection is available. The appliance decides whether to
encrypt the message or send it over a TLS connection based on the TLS setting in
the destination controls (Required, Preferred, or None) and the action defined in
the encryption content filter.
When creating the content filter, you can specify whether to always encrypt a
message or to attempt to send it over a TLS connection first, and if a TLS
connection is unavailable, to encrypt the message.
message or to attempt to send it over a TLS connection first, and if a TLS
connection is unavailable, to encrypt the message.
Email Security appliance will send a message based on the TLS settings for a
domain’s destination controls, if the encryption control filter attempts to send the
message over a TLS connection first.
domain’s destination controls, if the encryption control filter attempts to send the
message over a TLS connection first.
For more information on enabling TLS on destination controls, see the
“Customizing Listeners” chapter in the Cisco IronPort AsyncOS for Email
Advanced Configuration Guide.
“Customizing Listeners” chapter in the Cisco IronPort AsyncOS for Email
Advanced Configuration Guide.
Creating a Content Filter to Encrypt and Deliver Now
To create a content filter to encrypt a message and deliver it immediately, skipping
any further processing:
any further processing:
Step 1
Go to Mail Policies > Outgoing Content Filters.
Step 2
In the Filters section, click Add Filter.
Table 12-1
TLS Support on ESA Appliances
Destination Controls TLS
Setting
Setting
Action if TLS Connection
Available
Available
Action if TLS Connection
Unavailable
Unavailable
None
Encrypt envelope and
send
send
Encrypt envelope and
send
send
TLS Preferred
Send over TLS
Encrypt envelope and
send
send
TLS Required
Send over TLS
Retry/bounce message