When the delay keyword is selected, the next-hop mailer sends a message to the FROM address saying that the mail message was delayed. The definition of the delay keyword is made by each mailer and is not controlled by the sender. Each mailer in the path to the recipient that supports the DSN extension receives the same request.
When the failure keyword is selected, the next-hop mailer sends a message to the FROM address that the mail message delivery failed. Each mailer in the path to the recipient that supports the DSN extension receives the same request.
When the success keyword is selected, the next-hop mailer sends a message to the FROM address saying that the mail message was successfully delivered to the recipient. Each mailer in the path to the recipient that supports the DSN extension receives the same request.
In the absence of any other DSN settings (for example, no dsn, or a mailer in the path that does not support the DSN extension), a failure to deliver message always causes a nondelivery message to be generated. This nondelivery message is called a bounce.
This command is applicable to Multimedia Mail over Internet Protocol (MMoIP) dial peers.
DSNs are messages or responses that are automatically generated and sent to the sender or originator of an e-mail message by the Simple Mail Transfer Protocol (SMTP) server, notifying the sender of the status of the e-mail message. Specifications for DSN are described in RFC 1891, RFC 1892, RFC 1893, and RFC 1894.
The on-ramp DSN request is included as part of the fax-mail message sent by the on-ramp gateway when the matching MMoIP dial peer has been configured. The on-ramp DSN response is generated by the SMTP server when the fax-mail message is accepted. The DSN is sent back to the user defined by the mta send mail-from command. The off-ramp DSN is requested by the e-mail client. The DSN response is generated by the SMTP server when it receives a request as part of the fax-mail message.
DSNs are generated only if the mail client on the SMTP server is capable of responding to a DSN request.
Because the SMTP server generates the DSNs, you need to configure both mail from: and rcpt to: on the server for the DSN feature to work. For example:
mail from: <email@example.com>
rcpt to: <firstname.lastname@example.org> NOTIFY=SUCCESS,FAILURE,DELAY
Three different states can be reported back to the sender:
Delay--Indicates that the message was delayed in being delivered to the recipient or mailbox.
Success--Indicates that the message was successfully delivered to the recipient or mailbox.
Failure--Indicates that the SMTP server was unable to deliver the message to the recipient or mailbox.
Because these delivery states are not mutually exclusive, you can configure store-and-forward fax to generate these messages for all or any combination of these events.
DSN messages notify the sender of the status of a particular e-mail message that contains a fax TIFF image. Use the dsn command to specify which notification messages are sent to the user.
The dsn command allows you to select more than one notification option by reissuing the command and specifying a different notification option each time. To discontinue a specific notification option, use the no form of the command for that specific keyword.
If the failure keyword is not included when DSN is configured, the sender receives no notification of message delivery failure. Because a failure is usually significant, care should be taken to always include the f ailure keywordas part of the dsn command configuration.
This command applies to on-ramp store-and-forward fax functions.