User Guide

24-36
AsyncOS 9.1.2 for Cisco Email Security Appliances User Guide
Chapter 24 Configuring Routing and Delivery Features
Directing Bounced Email
Related Topics
• Handling Undeliverable Email, page 24-36
• Creating a New Bounce Profile, page 24-40
• Applying Bounce Profiles to Listeners, page 24-41
Handling Undeliverable Email
The AsyncOS operating system classifies undeliverable email, or “bounced messages,” into the
following categories:
You use the Bounce Profiles page on the Network menu in the GUI (or the
bounceconfig command) to
configure how AsyncOS handles hard and soft conversational bounces for each listener you create. You
create bounce profiles and then apply profiles to each listener via the Network > Listeners page (or the
listenerconfig command). You can also assign bounce profiles to specific messages using message
filters. (See Chapter 9, “Using Message Filters to Enforce Email Policies” for more information.)
Related Topics
• Notes on Soft and Hard Bounces, page 24-36
• Bounce Profile Parameters, page 24-37
• Hard Bounces and the status Command, page 24-38
• Conversational Bounces and SMTP Routes Message Filter actions, page 24-38
• Example Bounce Profiles, page 24-39
• Delivery Status Notification Format, page 24-39
• Delay Warning Messages, page 24-40
• Delay Warning Messages and Hard Bounces, page 24-40
Notes on Soft and Hard Bounces
• For conversational soft bounces, a soft bounce event is defined as each time a recipient delivery
temporarily fails. A single recipient may incur several soft bounce events. You use the Bounce
Profiles page or the
bounceconfig command to configure parameters for each soft bounce event.
(See Bounce Profile Parameters, page 24-37.)
“Conversational” bounces:
The remote domain bounces the message during the initial SMTP conversation.
Soft bounces A message that is temporarily undeliverable. For example, a user’s mailbox may be
full. These messages can be retried at a later time. (e.g. An SMTP 4XX error code.)
Hard bounces A message that is permanently undeliverable. For example, the user no longer exists
for that domain. These messages will not be retried. (e.g. An SMTP 5XX error code.)
“Delayed” (or “Non-conversational”) bounces:
The remote domain accepts the message for delivery, only to bounce it at a later time.
Soft bounces A message that is temporarily undeliverable. For example, a user’s mailbox may be
full. These messages can be retried at a later time. (e.g. An SMTP 4XX error code.)
Hard bounces A message that is permanently undeliverable. For example, the user no longer exists
for that domain. These messages will not be retried. (e.g. An SMTP 5XX error code.)