PDF 300-720 Study Guide

To allow the Cisco ESA to encrypt an email using the CRES (Cisco Registered Envelope Service), a provisioned email encryption profile must be configured on Cisco ESA. A provisioned email encryption profile is a type of encryption profile that specifies how messages are encrypted using CRES, such as the encryption key strength, the notification options, the branding settings, etc.

References: User Guide for AsyncOS 15.0 for Cisco Secure Email Gateway, page 12-4.

• System: This is the default list of trusted certificate authorities that is provided by Cisco and updated automatically. It contains the certificates of well-known and widely used certificate authorities, such as VeriSign, Thawte, and GoDaddy.
• Custom: This is the list of additional certificate authorities that you can add manually or import from a file. It allows you to trust certificates that are issued by your own or third-party certificate authorities that are not included in the system list.

To combat backscatter, which is a type of spam that consists of bounce messages sent to forged sender addresses, the administrator must enable the Bounce Verification feature under Security Settings. This feature allows the appliance to verify whether a bounce message is legitimate or not by checking if the original message was sent from the appliance. If not, the bounce message is considered as backscatter and can be dropped or quarantined. References: [Cisco Secure Email Gateway Administrator Guide - Configuring Bounce Verification]

Content filters are rules that allow Cisco ESA to perform actions on messages based on predefined or custom conditions, such as headers, envelope, body, attachments, etc.

The two primary components of content filters are:

• Conditions, which are the criteria that determine whether a message matches a content filter rule or not, such as message size, sender address, attachment type, etc.
• Actions, which are the operations that Cisco ESA performs on a message if it matches the conditions of a content filter rule, such as deliver, drop, quarantine, encrypt, etc.

The other options are not primary components of content filters on Cisco ESA.

References: User Guide for AsyncOS 15.0 for Cisco Secure Email Gateway, page 8-3 and page 8-4.