Cisco Cisco Email Security Appliance X1070 Troubleshooting Guide

Contributed by Nasir Shakour and Robert Sherwin, Cisco TAC
Engineers.
Aug 14, 2014

This document describes the differences between the "inital... wait" and "maximum... wait" configuration
values in the bounce configuration on the Cisco Email Security Appliance (ESA).

In the configuration options for bounceconfig, the "initial number of seconds to wait before retrying a
message" is the time to wait after the first unsuccessful attempt to deliver mail for a responsive mail server.

Please enter the initial number of seconds to wait before

retrying a message.

[60]> 

Note: By default, the ESA sets this value to 60 seconds.

Note: Unsuccessful attempts are 4xx SMTP response codes. Please see Simple Mail Transfer Protocol
(SMTP) Enhanced Status Codes Registry .

The "maximum number of seconds to wait before retrying a message" is recommended according to RFC
2821, section 4.5.4 Retry Strategies − to be greater than 1800 seconds.

Please enter the maximum number of seconds to wait before retrying a message.

[3600]> 

Note: By default, the ESA sets this value to 3600 seconds or 1 hour.

As for why it is the 'maximum' value, and not just a retry interval, as also mentioned in the same  RFC 2821,
section 4.5.4 Retry Strategies, "The sender MUST delay retrying a particular destination after one attempt has
failed.  In general, the retry interval SHOULD be at least 30 minutes; however, more sophisticated and
variable strategies will be beneficial when the SMTP client can determine the reason for non−delivery."

Therefore, if a new mail to a domain is successful, all mails that were previously queued and had retry
intervals will be re−attempted for delivery immediately.