(.NET Core C#) Build a multipart/related MIME Message

Demonstrates how to construct a multipart/related MIME message containing HTML and a related JPG image.

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// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

bool success;

// Start with an empty MIME object...
Chilkat.Mime mime = new Chilkat.Mime();

// Initialize it as multipart/related.
mime.NewMultipartRelated();

// Set a top-level MIME header field.
mime.SetHeaderField("Subject","Test HTML email with JPG image.");

// Generate a Content-ID.  This will contain random data that will allow
// the HTML's "img" tag to reference the image part in the MIME.
Chilkat.Crypt2 crypt = new Chilkat.Crypt2();
crypt.EncodingMode = "hex";

Chilkat.StringBuilder sbContentId = new Chilkat.StringBuilder();
sbContentId.Append("part1.");
sbContentId.Append(crypt.GenRandomBytesENC(4));
sbContentId.Append(".");
sbContentId.Append(crypt.GenRandomBytesENC(4));
sbContentId.Append("@chilkatsoft.com");

// Create the HTML body.
Chilkat.StringBuilder sbHtml = new Chilkat.StringBuilder();
sbHtml.Append("<html><head>\r\n");
sbHtml.Append("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\">\r\n");
sbHtml.Append("  </head>\r\n");
sbHtml.Append("  <body bgcolor=\"#FFFFFF\" text=\"#000000\">\r\n");
sbHtml.Append("    <p>This is a test.&nbsp; <img src=\"cid:CONTENT_ID\" height=\"20\" width=\"20\"></p>\r\n");
sbHtml.Append("  </body>\r\n");
sbHtml.Append("</html>\r\n");
int numReplacements = sbHtml.Replace("CONTENT_ID",sbContentId.GetAsString());

// Create the HTML MIME part.
Chilkat.Mime htmlMime = new Chilkat.Mime();
htmlMime.SetBodyFromHtml(sbHtml.GetAsString());
htmlMime.Encoding = "8bit";
htmlMime.Charset = "utf-8";

// Load our JPG image from a file.
Chilkat.FileAccess fac = new Chilkat.FileAccess();
byte[] jpgBytes = null;
jpgBytes = fac.ReadEntireFile("qa_data/jpg/starfish20.jpg");

// Create an image/jpeg MIME part.
Chilkat.Mime jpgMime = new Chilkat.Mime();
jpgMime.SetBodyFromBinary(jpgBytes);
// Setting the following properties has the effect of adding
// the Content-Type, Content-Transfer-Encoding, and Content-Disposition header fields.
// These header fields could also be set via the SetHeaderField method, in which case
// the values of the affected properties would be updated.
jpgMime.ContentType = "image/jpeg";
jpgMime.Name = "starfish20.jpg";
jpgMime.Encoding = "base64";
jpgMime.Disposition = "inline";
jpgMime.Filename = "starfish20.jpg";

Chilkat.StringBuilder sbContentIdHdr = new Chilkat.StringBuilder();
sbContentIdHdr.Append("<CONTENT_ID>");
numReplacements = sbContentIdHdr.Replace("CONTENT_ID",sbContentId.GetAsString());
jpgMime.SetHeaderField("Content-ID",sbContentIdHdr.GetAsString());

// Add both parts as children of the multipart/related
mime.AppendPart(htmlMime);
mime.AppendPart(jpgMime);
Debug.WriteLine(mime.GetMime());

// --------------------------------------------------------------
// --------------------------------------------------------------
// This example builds the following MIME message.  The boundary
// and Content-ID strings contain random data and will be different.  

// Content-Type: multipart/related; boundary="------------A940F1230E6F0105F03DB2CB"
// Subject: Test HTML email with JPG image.
// 
// --------------A940F1230E6F0105F03DB2CB
// Content-Type: text/html; charset="utf-8"
// Content-Transfer-Encoding: 8bit
// 
// <html><head>
// <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
//   </head>
//   <body bgcolor="#FFFFFF" text="#000000">
//     <p>This is a test.&nbsp; <img src="cid:part1.E16AE3B4.1505C436@chilkatsoft.com" height="20" width="20"></p>
//   </body>
// </html>
// 
// --------------A940F1230E6F0105F03DB2CB
// Content-Transfer-Encoding: base64
// Content-Type: image/jpeg; name="starfish20.jpg"
// Content-Disposition: inline; filename="starfish20.jpg"
// Content-ID: <part1.E16AE3B4.1505C436@chilkatsoft.com>
// 
// /9j/4AAQSkZJRgABAQEASABIAAD//gAmRmlsZSB3cml0dGVuIGJ5IEFkb2JlIFBob3Rvc2hvcD8g
// NC4w/9sAQwAQCwwODAoQDg0OEhEQExgoGhgWFhgxIyUdKDozPTw5Mzg3QEhcTkBEV0U3OFBtUVdf
// YmdoZz5NcXlwZHhcZWdj/9sAQwEREhIYFRgvGhovY0I4QmNjY2NjY2NjY2NjY2NjY2NjY2NjY2Nj
// Y2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2Nj/8IAEQgAFAAUAwERAAIRAQMRAf/EABcAAAMBAAAA
// AAAAAAAAAAAAAAIDBAX/xAAYAQADAQEAAAAAAAAAAAAAAAABAgMEAP/aAAwDAQACEAMQAAAB2kZY
// NNEijWKddfTmLgALWH//xAAbEAACAgMBAAAAAAAAAAAAAAABAgMRAAQSE//aAAgBAQABBQL0XqN+
// pM2aqJGMiqFFCyg7z//EABwRAAICAgMAAAAAAAAAAAAAAAERAAIQIQMSUf/aAAgBAwEBPwHqU5aq
// Axx+y1tMQl4elj//xAAcEQEAAQUBAQAAAAAAAAAAAAABEQACEBIhA1H/2gAIAQIBAT8B3Bhqy7Zc
// enyiwmGgDhiOzj//xAAdEAABAwUBAAAAAAAAAAAAAAABAAIREBIhIkFR/9oACAEBAAY/ArZyn+Cg
// xtxWuJaoCnqDuin/xAAcEAABBAMBAAAAAAAAAAAAAAABABEhYRAxQVH/2gAIAQEAAT8hkEwPUUR9
// DYfE4nxtRpIkBTsayuALIiuY/9oADAMBAAIAAwAAABDWPTsf/8QAGhEAAwADAQAAAAAAAAAAAAAA
// AAEREDFBIf/aAAgBAwEBPxC0DVPcWm+Ce4OesrkE6bjH/8QAGBEBAQEBAQAAAAAAAAAAAAAAAREA
// QRD/2gAIAQIBAT8QahMiOc8YgSrnTY3ELclHXn//xAAcEAEBAAIDAQEAAAAAAAAAAAABEQAhMUFx
// EFH/2gAIAQEAAT8Qn3igmSZSj+c4N4zapMy9IjFV98wncN2iuLFsCEbDGxQkI6RO/n//2Q==
// 
// --------------A940F1230E6F0105F03DB2CB--
//