Cisco Cisco Email Security Appliance C170 Guia Do Utilizador

the maximum 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.

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).

Time in Queue Messages (delay notification messages) generated by the system also use the DSN 
format. Change the default parameters by using the Bounce Profiles page on the Network menu (or the 

bounceconfig

 command) to edit existing or create new bounce profiles and change the default values 

for:

The minimum interval between sending delay warning messages.

The maximum number of delay warning messages to send per recipient. 

Note that it is possible to receive both a delay warning and a hard bounce for the same message 
simultaneously, if you have set a very small durations for both the “Maximum Time in Queue” setting 
and the minimum interval setting for “Send Delay Warning Messages.” Cisco Systems recommends 
using the default values for these settings as a minimum if you choose to enable sending of delay warning 
messages.

Further, delay warning messages and bounce messages originated by the appliance may be delayed by 
as much as 15 minutes during processing.

100

100 seconds

60 seconds

120 seconds