(Delphi DLL) 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 for Delphi Downloads Chilkat non-ActiveX DLL for Delphi Chilkat ActiveX DLL for Delphi * The examples here use the non-ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Mime, StringArray, HtmlToText, Email;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
email: HCkEmail;
h2t: HCkHtmlToText;
sa: HCkStringArray;
numFinalRecipients: Integer;
i: Integer;
headersText: PWideChar;
mime: HCkMime;
origEmail: HCkEmail;

begin
// 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) then
  begin
    Memo1.Lines.Add(CkEmail__lastErrorText(email));
    Exit;
  end;

// Verify this is a multipart/report email..
if (CkEmail_IsMultipartReport(email) = False) then
  begin
    Memo1.Lines.Add('Not a multipart/report email.');
    Exit;
  end;

// Get the body that is to be displayed to a human in an email program (such as Outlook).
if (CkEmail_HasPlainTextBody(email) = True) then
  begin
    Memo1.Lines.Add('Plain text body:');
    // println email.GetPlainTextBody();
  end
else
  begin
    if (CkEmail_HasHtmlBody(email) = True) then
      begin
        // Convert HTML to plain-text..
        h2t := CkHtmlToText_Create();
        Memo1.Lines.Add('HTML body converted to plain-text:');
        Memo1.Lines.Add(CkHtmlToText__toText(h2t,CkEmail__getHtmlBody(email)));
      end
    else
      begin
        Memo1.Lines.Add('Has no plain-text or HTML body...');
      end;
  end;
Memo1.Lines.Add('---------------------------------');

// Now get information from the message/delivery-status part (or the message/disposition-notification part)
Memo1.Lines.Add('--- Delivery Status Information:');
Memo1.Lines.Add('Status: ' + CkEmail__getDeliveryStatusInfo(email,'Status'));
Memo1.Lines.Add('Action: ' + CkEmail__getDeliveryStatusInfo(email,'Action'));
Memo1.Lines.Add('Reporting-MTA: ' + CkEmail__getDeliveryStatusInfo(email,'Reporting-MTA'));

sa := CkEmail_GetDsnFinalRecipients(email);
numFinalRecipients := CkStringArray_getCount(sa);
i := 0;
while i < numFinalRecipients do
  begin
    Memo1.Lines.Add('final recipient: ' + CkStringArray__getString(sa,i));
    i := i + 1;
  end;

CkStringArray_Dispose(sa);

Memo1.Lines.Add('---------------------------------');

// 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) then
  begin
    Memo1.Lines.Add('The text/rfc822-headers part exists..');
    Memo1.Lines.Add('');
    Memo1.Lines.Add(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.
    Memo1.Lines.Add('MIME To header:');
    Memo1.Lines.Add(CkMime__getHeaderField(mime,'To'));
  end;

Memo1.Lines.Add('---------------------------------');

// 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) then
  begin
    // Get the 1st attachment message (assume we don't have more than one attached message)
    origEmail := CkEmail_GetAttachedMessage(email,0);
    if (CkEmail_getLastMethodSuccess(email) = True) then
      begin
        Memo1.Lines.Add('Attached message subject: ' + CkEmail__subject(origEmail));
        // Do whatever else you want..
        CkEmail_Dispose(origEmail);
      end;
  end;

CkEmail_Dispose(email);
        CkHtmlToText_Dispose(h2t);
    CkMime_Dispose(mime);

end;