Руководство Пользователя для Cisco Cisco Email Security Appliance X1070
5-9
Cisco AsyncOS 8.5.5 for Email Security User Guide
Chapter 5 Configuring the Gateway to Receive Email
Listening for Connection Requests by Creating a Listener via the GUI
Step 4
(Optional) Configure settings for controlling parsing in SMTP “MAIL FROM” and “RCPT TO”
commands as desfined in the following table.
commands as desfined in the following table.
Setting
Description
Address Parser Type
Choose how strictly the appliance adheres to the RFC2821 standard using
one of the following parser types:
one of the following parser types:
Strict Mode:
Strict mode tries to follow RFC 2821. In Strict mode, the address parser
follows RFC 2821 rules with the following exceptions/enhancements:
follows RFC 2821 rules with the following exceptions/enhancements:
•
Space is allowed after the colon, as in “MAIL FROM:
<joe@example.com>”.
<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.”).
a username of “J.D.”).
Some of the additional options below may be enabled which technically
would violate RFC 2821.
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:
AsyncOS. It does its best to “find” an email address and:
•
Ignores comments. It supports nested comments (anything found in
parenthesis) and ignores them.
parenthesis) and ignores them.
•
Does not require angle brackets around email addresses provided in
“RCPT TO” and “MAIL FROM” commands.
“RCPT TO” and “MAIL FROM” commands.
•
Allows multiple nested angle brackets (it searches for the email address
in the deepest nested level).
in the deepest nested level).
Allow 8-bit User Names If enabled, allow 8-bit characters in the username portion of the address
without escaping.
Allow 8-bit Domain
Names
Names
If enabled, allow 8-bit characters in the domain portion of the address.