(PureBasic) Processing a multipart/report Delivery Status Notification (Bounce Notification)

See more Email Object Examples

This example discusses the format of Delivery Status Notification emails and how to process them.

Note: This example requires Chilkat v11.0.0 or greater.

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Chilkat PureBasic Module

IncludeFile "CkMime.pb"
IncludeFile "CkHtmlToText.pb"
IncludeFile "CkJsonObject.pb"
IncludeFile "CkEmail.pb"

Procedure ChilkatExample()

    success.i = 0

    ; Here are the MIME structures, showing the content-type and nesting of the MIME parts of three sample
    ; multipart/report DSN (Delivery Status Notification) emails.

    ; This 1st sample includes a "text/rfc822-headers" MIME subpart. 

    ; multipart/report
    ;     text/plain
    ;     message/delivery-status
    ;     text/rfc822-headers
    ;     message/rfc822

    ; This 2nd sample lacks the text/rfc-headers part, but the "report type" information
    ; is offered in both plain-text and HTML formats.

    ; multipart/report
    ;     multipart/alternative
    ;         text/plain
    ;         text/html
    ;     message/delivery-status
    ;     message/rfc822

    ; ----------------------------------------------------------------------------------------------------

    ; A multipart/report MIME delivery status notification follows a specific format defined by the Internet Engineering Task Force (IETF) in RFC 3464, 
    ; which outlines the "An Extensible Message Format for Delivery Status Notifications" standard. The format consists of multiple parts within a 
    ; multipart/report structure. Here's an overview of the main parts involved:
    ; 
    ; The 1st sub-part under multipart/report is the body of the DSN to be displayed by the email client (such as Outlook).
    ; It can be a simple text/plain body, or it can be multipart/alternative and offer a few alternative format, typically plain-text and HTML.
    ; HTML is best for viewing a program such as Outlook. 
    ; This part of the multipart/report is not structured for programmatic processing.  It's meant to be viewed by a human.

    ; --------------------
    ; The "message/delivery-status" part within a multipart/report MIME structure follows a specific format to provide details about the delivery status
    ; of an email message.  Here's an overview of the format and the key components within the "message/delivery-status" part:
    ; 
    ; (1) Content-Type and Reporting-UA:
    ; The "message/delivery-status" part begins with the Content-Type header specifying "message/delivery-status". 
    ; It may also include a Reporting-UA (Reporting User Agent) field that identifies the software or system generating the delivery status notification.
    ; 
    ; For example:
    ; 
    ; Content-Type: message/delivery-status
    ; Reporting-UA: Example Mail System 1.0
    ; 
    ; (2) Fields:
    ; The "message/delivery-status" part contains a series of fields, each providing specific information about the delivery status. 
    ; These fields are structured as key-value pairs.
    ; 
    ; Common fields include:
    ; 
    ;     Final-Recipient: Specifies the recipient for whom the delivery status is being reported.
    ;     Action: Describes the action performed by the reporting system (e.g., failed, delivered, delayed, etc.).
    ;     Status: Indicates the status code or reason for the delivery attempt result.
    ;     Remote-MTA: Specifies the host or system that attempted the delivery.
    ;     Diagnostic-Code: Provides additional diagnostic information, such as error codes or explanations.
    ; 
    ; For example:
    ; 
    ; Final-Recipient: rfc822; john.doe@example.com
    ; Action: failed
    ; Status: 5.1.1
    ; Remote-MTA: smtp.example.com
    ; Diagnostic-Code: smtp; 550 Requested action not taken: mailbox unavailable
    ; 
    ; (3) Additional Fields:
    ; Additional fields may be included in the "message/delivery-status" part to provide further information about the delivery attempt. 
    ; These fields can vary depending on the implementation or specific needs of the system generating the delivery status notification.
    ; For example:
    ; 
    ; X-Spam-Flag: YES
    ; X-Spam-Score: 7.2
    ; 
    ; Note: The specific fields and their values within the "message/delivery-status" part can vary depending on the implementation
    ; or the email server/application generating the delivery status notification. The structure described above represents the standard format
    ; as defined in RFC 3464, but variations may exist in practice.

    ; --------------------

    ; The "text/rfc822-headers" MIME part, if included, contains the headers of the original email message
    ; for which the delivery status notification is being generated. It provides a subset of the headers from the original message,
    ; typically excluding the message body and attachments.
    ; 
    ; The purpose of including the "text/rfc822-headers" part is to provide contextual information about the original message.
    ; It allows the recipient to review the original headers, such as the subject, sender, recipients, date, and other relevant information,
    ; in order to understand the context and details of the email message for which the delivery status notification is being generated.
    ; 
    ; Note that the specific headers included in the "text/rfc822-headers" part can vary based on the implementation or requirements
    ; of the system generating the delivery status notification.

    ; --------------------

    ; If the message/rfc822 part is present, it contains the full MIME of the email that was not delivered.
    ; In Chilkat terminology, this is an attached message.

    ; OK, let's write code to process a multipart/report email.

    email.i = CkEmail::ckCreate()
    If email.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkEmail::ckLoadEml(email,"qa_data/eml/deliveryStatus.eml")
    ; success = email.LoadEml("qa_data/eml/sample_multipart_report.eml");
    If success = 0
        Debug CkEmail::ckLastErrorText(email)
        CkEmail::ckDispose(email)
        ProcedureReturn
    EndIf

    ; Verify this is a multipart/report email..
    If CkEmail::ckIsMultipartReport(email) = 0
        Debug "Not a multipart/report email."
        CkEmail::ckDispose(email)
        ProcedureReturn
    EndIf

    ; Get the body that is to be displayed to a human in an email program (such as Outlook).
    If CkEmail::ckHasPlainTextBody(email) = 1
        Debug "Plain text body:"
        ; println email.GetPlainTextBody();
    Else
        If CkEmail::ckHasHtmlBody(email) = 1
            ; Convert HTML to plain-text..
            h2t.i = CkHtmlToText::ckCreate()
            If h2t.i = 0
                Debug "Failed to create object."
                ProcedureReturn
            EndIf

            Debug "HTML body converted to plain-text:"
            Debug CkHtmlToText::ckToText(h2t,CkEmail::ckGetHtmlBody(email))
        Else
            Debug "Has no plain-text or HTML body..."
        EndIf

    EndIf

    Debug "---------------------------------"

    ; Now get information from the message/delivery-status part (or the message/disposition-notification part)
    Debug "--- Delivery Status Information:"
    Debug "Status: " + CkEmail::ckGetDeliveryStatusInfo(email,"Status")
    Debug "Action: " + CkEmail::ckGetDeliveryStatusInfo(email,"Action")
    Debug "Reporting-MTA: " + CkEmail::ckGetDeliveryStatusInfo(email,"Reporting-MTA")

    jsonDsnInfo.i = CkJsonObject::ckCreate()
    If jsonDsnInfo.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkEmail::ckGetDsnInfo(email,jsonDsnInfo)
    CkJsonObject::setCkEmitCompact(jsonDsnInfo, 0)
    Debug CkJsonObject::ckEmit(jsonDsnInfo)

    Debug "---------------------------------"

    ; If the multipart/report contains a text/rfc822-headers, it can be retrieved like this:
    headersText.s = CkEmail::ckGetNthTextPartOfType(email,0,"text/rfc822-headers",0,0)
    If CkEmail::ckLastMethodSuccess(email) = 1
        Debug "The text/rfc822-headers part exists.."
        Debug ""
        Debug headersText

        ; If you wish to process the headers, you can load them into a MIME object and use the Chilkat MIME functionality to examine the headers.
        mime.i = CkMime::ckCreate()
        If mime.i = 0
            Debug "Failed to create object."
            ProcedureReturn
        EndIf

        CkMime::ckLoadMime(mime,headersText)

        ; Do whatever you want.. 
        ; For example, look at the "To" header.
        Debug "MIME To header:"
        Debug CkMime::ckGetHeaderField(mime,"To")
    EndIf

    Debug "---------------------------------"

    ; Finally, if the original email was attached, you can load it into another Chilkat Email object instance and
    ; do what you want with it..

    If CkEmail::ckNumAttachedMessages(email) > 0
        ; Get the 1st attachment message (assume we don't have more than one attached message)
        origEmail.i = CkEmail::ckCreate()
        If origEmail.i = 0
            Debug "Failed to create object."
            ProcedureReturn
        EndIf

        success = CkEmail::ckGetAttachedEmail(email,0,origEmail)
        If success = 1
            Debug "Attached message subject: " + CkEmail::ckSubject(origEmail)
            ; Do whatever else you want..
        EndIf

    EndIf



    CkEmail::ckDispose(email)
    CkHtmlToText::ckDispose(h2t)
    CkJsonObject::ckDispose(jsonDsnInfo)
    CkMime::ckDispose(mime)
    CkEmail::ckDispose(origEmail)


    ProcedureReturn
EndProcedure