(VB.NET UWP/WinRT) Build a multipart/related MIME Message

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

Chilkat Universal Windows Platform (UWP) / WinRT Downloads

Chilkat for the Universal Windows Platform (UWP)

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

Dim success As Boolean

' Start with an empty MIME object...
Dim mime As 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.
Dim crypt As New Chilkat.Crypt2
crypt.EncodingMode = "hex"

Dim sbContentId As 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.
Dim sbHtml As New Chilkat.StringBuilder
sbHtml.Append("<html><head>" & vbCrLf)
sbHtml.Append("<meta http-equiv=""Content-Type"" content=""text/html; charset=utf-8"">" & vbCrLf)
sbHtml.Append("  </head>" & vbCrLf)
sbHtml.Append("  <body bgcolor=""#FFFFFF"" text=""#000000"">" & vbCrLf)
sbHtml.Append("    <p>This is a test.&nbsp; <img src=""cid:CONTENT_ID"" height=""20"" width=""20""></p>" & vbCrLf)
sbHtml.Append("  </body>" & vbCrLf)
sbHtml.Append("</html>" & vbCrLf)
Dim numReplacements As Integer = sbHtml.Replace("CONTENT_ID",sbContentId.GetAsString())

' Create the HTML MIME part.
Dim htmlMime As New Chilkat.Mime
htmlMime.SetBodyFromHtml(sbHtml.GetAsString())
htmlMime.Encoding = "8bit"
htmlMime.Charset = "utf-8"

' Load our JPG image from a file.
Dim fac As New Chilkat.FileAccess
Dim jpgBytes() As Byte
jpgBytes = fac.ReadEntireFile("qa_data/jpg/starfish20.jpg")

' Create an image/jpeg MIME part.
Dim jpgMime As 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"

Dim sbContentIdHdr As 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--
'