Cisco Cisco Email Security Appliance C190 Guia Do Utilizador

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Cisco IronPort AsyncOS 7.5 for Email Advanced Configuration Guide

OL-25137-01

Chapter 1 Customizing Listeners

Figure 1-6

Listeners SMTP Address Parsing Options

SMTP address parsing controls how strict the AsyncOS address parser behaves
for the SMTP “MAIL FROM” and “RCPT TO” commands. SMTP address
parsing has two modes: Strict and Loose as well as several other parsing options
(configured independently of the address parsing mode).

Selecting a parsing mode or type is deciding whether you want your appliance to
strictly adhere to the standards of RFC2821.

Strict Mode

Strict mode tries to follow RFC 2821. In Strict mode, the address parser
follows RFC 2821 rules with the following exceptions/enhancements:

–

Space is allowed after the colon, as in “MAIL FROM:
<joe@example.com>”.

–

Underscores are allowed in the domain name.

–

“MAIL FROM” and “RCPT TO” commands are case-insensitive.

–

Periods are not treated specially (for example, RFC 2821 does not allow
a username of “J.D.”).

Some of the additional options below may be enabled which technically
would violate RFC 2821.

Loose Mode

The loose parser is basically the existing behavior from previous versions of
AsyncOS. It does its best to “find” an email address and:

–

Ignores comments. It supports nested comments (anything found in
parenthesis) and ignores them.