Cisco Cisco Email Security Appliance C170 Guia Do Utilizador
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Cisco AsyncOS 8.5.5 for Email Security User Guide
Chapter 23 Configuring Routing and Delivery Features
Directing Bounced Email
Handling Undeliverable Email
The AsyncOS operating system classifies undeliverable email, or “bounced messages,” into the
following categories:
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
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
for more information.)
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
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
•
By default, the system generates a bounce message and sends it to the original sender for each hard
bounced recipient. (The message is sent to the address defined in the Envelope Sender address of
the message envelope. Envelope From is also commonly referred to as the Envelope Sender.) You
can disable this feature and instead rely on log files for information about hard bounces. (See the
“Logging” chapter.)
bounced recipient. (The message is sent to the address defined in the Envelope Sender address of
the message envelope. Envelope From is also commonly referred to as the Envelope Sender.) You
can disable this feature and instead rely on log files for information about hard bounces. (See the
“Logging” chapter.)
•
Soft bounces become hard bounces after the maximum time in queue or the maximum number of
retries, whichever comes first.
retries, whichever comes first.
“Conversational” bounces:
The remote domain bounces the message during the initial SMTP conversation.
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.)
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.)
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.
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.)
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.)
for that domain. These messages will not be retried. (e.g. An SMTP 5XX error code.)