Cisco Cisco Email Security Appliance X1050 Information Guide
Why does the ESA accept and deliver mail
messages containing bare < LF > characters?
messages containing bare < LF > characters?
Document ID: 117979
Contributed by Nasir Shakour and Enrico Werner, Cisco TAC
Engineers.
Jul 17, 2014
Engineers.
Jul 17, 2014
Contents
Question:
Question:
Why does the ESA accept and deliver mail messages containing bare <LF> characters?
SMTP commands and message data are transmitted in "lines". Lines consist of zero or more data characters
terminated by a <CR> character followed immediately by a <LF> character. This sequence is denoted
using the string <CRLF>. RFC2821 requires SMTP clients and servers to not accept any other character (such
as a "bare" <LF>) or to generate any other sequence as a line terminator.
terminated by a <CR> character followed immediately by a <LF> character. This sequence is denoted
using the string <CRLF>. RFC2821 requires SMTP clients and servers to not accept any other character (such
as a "bare" <LF>) or to generate any other sequence as a line terminator.
The MTA component of the ESA accepts and delivers messages that include bare <LF> characters as line
delimiters, in the interest of better interoperability and in response to overwhelming customer requests. ESA
users have the choice to pass bare <LF> or <CR> line delimiters through or to "clean" these delimiters,
replacing the single characters with the complete <CRLF>.
delimiters, in the interest of better interoperability and in response to overwhelming customer requests. ESA
users have the choice to pass bare <LF> or <CR> line delimiters through or to "clean" these delimiters,
replacing the single characters with the complete <CRLF>.
Updated: Jul 17, 2014
Document ID: 117979