Cisco Cisco Email Security Appliance C670 Libro bianco

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4

Scenario: Business-to-Business

Organizations A and B want all the messages communicated between 

them to be signed and encrypted using S/MIME. Organization A has 

a Cisco Email Security Appliance (one of the Cisco Email Security 

deployment options) to perform S/MIME security services at the 

gateway level. Organization B has a third-party application to perform  

S/MIME security services at the gateway level.

Organization A

Organization B

Email Security Appliance

Email Client

Bob

Email Client

Legend

Message from

A to B

Message from

B to A

Gateway

Dave

Note:

 The current example assumes that organization B is using a third-party 

application to perform S/MIME security services. In the real world, this can be 

any application or appliance (including Cisco Email Security Appliance) that can 

perform S/MIME security services at the gateway level.

Organization A sending a message to Organization B:
1. Bob (Organization A) uses an email client to send an unsigned and 

unencrypted message to Dave (Organization B).

2. Cisco Email Security Appliance (ESA) in Organization A signs and 

encrypts the messages and sends it to Organization B.

3. The third-party application at the gateway of Organization B decrypts 

and verifies the message.

4. Dave receives an unencrypted and unsigned message.

Organization B sending a message to Organization A:
1. Dave (Organization B) uses an email client to send an unsigned and 

unencrypted message to Bob (Organization A).

2. The third-party application at the gateway of Organization B signs 

and encrypts the message and sends it to Organization A.

3. Cisco Email Security Appliance in Organization A decrypts and 

verifies the message.

4. Bob receives an unencrypted and unsigned message.

Scenario: Business-to-Consumer

Organizations A and B want all the messages communicated between 

them to be signed and encrypted using S/MIME. Organization A has 

Cisco Email Security Appliance to perform S/MIME security services at 

the gateway level. Organization B has configured the email clients of all 

the users to perform S/MIME security services.

Organization A

Organization B

Email Security Appliance

Email Client

Alice

Email Client

Legend

Message from

A to B

Message from

B to A

Gateway

Erin

Cisco Email Security How-To Guide

How-To Secure Communications

Cisco Public