C
C
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.Chilkat C Downloads
#include <C_CkEmail.h>
#include <C_CkHtmlToText.h>
#include <C_CkJsonObject.h>
#include <C_CkMime.h>
void ChilkatSample(void)
{
BOOL success;
HCkEmail email;
HCkHtmlToText h2t;
HCkJsonObject jsonDsnInfo;
const char *headersText;
HCkMime mime;
HCkEmail origEmail;
success = FALSE;
// 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 = CkEmail_Create();
success = CkEmail_LoadEml(email,"qa_data/eml/deliveryStatus.eml");
// success = email.LoadEml("qa_data/eml/sample_multipart_report.eml");
if (success == FALSE) {
printf("%s\n",CkEmail_lastErrorText(email));
CkEmail_Dispose(email);
return;
}
// Verify this is a multipart/report email..
if (CkEmail_IsMultipartReport(email) == FALSE) {
printf("Not a multipart/report email.\n");
CkEmail_Dispose(email);
return;
}
// Get the body that is to be displayed to a human in an email program (such as Outlook).
if (CkEmail_HasPlainTextBody(email) == TRUE) {
printf("Plain text body:\n");
// println email.GetPlainTextBody();
}
else {
if (CkEmail_HasHtmlBody(email) == TRUE) {
// Convert HTML to plain-text..
h2t = CkHtmlToText_Create();
printf("HTML body converted to plain-text:\n");
printf("%s\n",CkHtmlToText_toText(h2t,CkEmail_getHtmlBody(email)));
}
else {
printf("Has no plain-text or HTML body...\n");
}
}
printf("---------------------------------\n");
// Now get information from the message/delivery-status part (or the message/disposition-notification part)
printf("--- Delivery Status Information:\n");
printf("Status: %s\n",CkEmail_getDeliveryStatusInfo(email,"Status"));
printf("Action: %s\n",CkEmail_getDeliveryStatusInfo(email,"Action"));
printf("Reporting-MTA: %s\n",CkEmail_getDeliveryStatusInfo(email,"Reporting-MTA"));
jsonDsnInfo = CkJsonObject_Create();
CkEmail_GetDsnInfo(email,jsonDsnInfo);
CkJsonObject_putEmitCompact(jsonDsnInfo,FALSE);
printf("%s\n",CkJsonObject_emit(jsonDsnInfo));
printf("---------------------------------\n");
// If the multipart/report contains a text/rfc822-headers, it can be retrieved like this:
headersText = CkEmail_getNthTextPartOfType(email,0,"text/rfc822-headers",FALSE,FALSE);
if (CkEmail_getLastMethodSuccess(email) == TRUE) {
printf("The text/rfc822-headers part exists..\n");
printf("\n");
printf("%s\n",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 = CkMime_Create();
CkMime_LoadMime(mime,headersText);
// Do whatever you want..
// For example, look at the "To" header.
printf("MIME To header:\n");
printf("%s\n",CkMime_getHeaderField(mime,"To"));
}
printf("---------------------------------\n");
// 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_getNumAttachedMessages(email) > 0) {
// Get the 1st attachment message (assume we don't have more than one attached message)
origEmail = CkEmail_Create();
success = CkEmail_GetAttachedEmail(email,0,origEmail);
if (success == TRUE) {
printf("Attached message subject: %s\n",CkEmail_subject(origEmail));
// Do whatever else you want..
}
}
CkEmail_Dispose(email);
CkHtmlToText_Dispose(h2t);
CkJsonObject_Dispose(jsonDsnInfo);
CkMime_Dispose(mime);
CkEmail_Dispose(origEmail);
}