Cisco Cisco Email Security Appliance C170 Guia Do Utilizador

retry interval of 60 seconds. Thus, the second retry attempt is made at 
approximately t=120. Immediately after this retry attempt, the system generates a 
hard bounce message for that recipient because the maximum number of retries is 
two.

100

100 seconds

60 seconds

120 seconds

In Example 2, the first delivery attempt is made at t=0 and the first retry is made 
at t=60. The system hard bounces the message immediately before the next 
delivery attempt (scheduled to occur at t=120) because it has exceeded the 
maximum time in queue of 100 seconds.

Bounce messages generated by the system, by default, use the Delivery Status 
Notification (DSN) format for both hard and soft bounces. DSN is a format 
defined by RFC 1894 (see 

http://www.faqs.org/rfcs/rfc1894.html

) that 

“defines a MIME content-type that may be used by a message transfer agent 
(MTA) or electronic mail gateway to report the result of an attempt to deliver a 
message to one or more recipients.” By default, the delivery status notification 
includes an explanation of the delivery status and the original message if the 
message size is less than 10k. If the message size is greater than 10k, the delivery 
status notification includes the message headers only. If the message headers 
exceed 10k, the delivery status notification truncates the headers. If you want 
include messages (or message headers) that are greater than 10k in the DSN, you 
can use the 

max_bounce_copy

 parameter in the 

bounceconfig

 command (this 

parameter is only available from the CLI).