Cisco Cisco Email Security Appliance C170 Guia Do Utilizador

Cisco IronPort AsyncOS supports several forms of email authentication, including Sender Policy 
Framework (SPF), Sender ID Framework (SIDF), DomainKeys and DomainKeys Identified Mail 
(DKIM). 

DomainKeys and DKIM verify the authenticity of email based on a signing key used by the sender. SPF 
and SIDF are methods for verifying the authenticity of email based on DNS TXT records. SPF and SIDF 
allow the owner of an Internet domain to use a special format of DNS records to designate which 
machines are authorized to send email for that domain.

This chapter contains the following sections: 

Cisco IronPort AsyncOS supports several forms of email authentication to prevent email forgery. To 
verify incoming mail, AsyncOS supports Sender Policy Framework (SPF), Sender ID Framework 
(SIDF), and DomainKeys Identified Mail (DKIM). To sign outgoing mail, AsyncOS supports 
DomainKeys and DKIM.

With DomainKeys or DKIM email authentication, the sender signs the email using public key 
cryptography. The verified domain can then be used to detect forgeries by comparing it with the domain 
in the From: (or Sender:) header of the email. The current version of AsyncOS supports email signing 
for DomainKeys, and it supports both email signing and verification for DKIM. For more information 
about DomainKeys and DKIM, see 

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