(VB.NET) Send HTML Email with External CSS as Related Item

Demonstrates how to compose an HTML email with an external CSS file included as a related item and referenced by CID (Content-ID).

Chilkat .NET Downloads

Chilkat .NET Framework

Chilkat for .NET Core

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

' The mailman object is used for sending and receiving email.
Dim mailman As New Chilkat.MailMan

' Use your SMTP server hostname.  This example uses office365, but it could be any SMTP server..
mailman.SmtpHost = "outlook.office365.com"
mailman.SmtpPort = 587
mailman.StartTLS = True

' Set the SMTP login/password
mailman.SmtpUsername = "OFFICE365-SMTP-LOGIN"
mailman.SmtpPassword = "OFFICE365-SMTP-PASSWORD"

' Create a new email object
Dim email As New Chilkat.Email
email.Subject = "HTML Email with embedded CSS"
email.From = "Chilkat Support <my-office365-user@mydomain.com>"
email.AddTo("Chilkat Support","support@chilkatsoft.com")

Dim sbCss As New Chilkat.StringBuilder
Dim bCrlf As Boolean = True
sbCss.AppendLine("body {",bCrlf)
sbCss.AppendLine("    background-color: powderblue;",bCrlf)
sbCss.AppendLine("}",bCrlf)
sbCss.AppendLine("h1 {",bCrlf)
sbCss.AppendLine("    color: blue;",bCrlf)
sbCss.AppendLine("}",bCrlf)
sbCss.AppendLine("p {",bCrlf)
sbCss.AppendLine("    color: red;",bCrlf)
sbCss.AppendLine("}",bCrlf)

' It's possible to add a CSS file directly by calling AddRelatedFile.
' This example will add the CSS from a string.
Dim filenameInHtml As String = "styles.css"
Dim contentIdCss As String = email.AddRelatedString(filenameInHtml,sbCss.GetAsString(),"utf-8")
If (email.LastMethodSuccess <> True) Then
    Debug.WriteLine(email.LastErrorText)
    Exit Sub
End If


' The src attribute for the image tag is set to the contentIdCss:
Dim sbHtml As New Chilkat.StringBuilder
sbHtml.AppendLine("<!DOCTYPE html>",bCrlf)
sbHtml.AppendLine("<html>",bCrlf)
sbHtml.AppendLine("<head>",bCrlf)
sbHtml.AppendLine("  <link rel=""stylesheet"" href=""cid:CONTENT_ID_CSS"">",bCrlf)
sbHtml.AppendLine("</head>",bCrlf)
sbHtml.AppendLine("<body>",bCrlf)
sbHtml.AppendLine("",bCrlf)
sbHtml.AppendLine("<h1>This is a heading</h1>",bCrlf)
sbHtml.AppendLine("<p>This is a paragraph.</p>",bCrlf)
sbHtml.AppendLine("",bCrlf)
sbHtml.AppendLine("</body>",bCrlf)
sbHtml.AppendLine("</html>",bCrlf)

Dim numReplacements As Integer = sbHtml.Replace("CONTENT_ID_CSS",contentIdCss)

email.SetHtmlBody(sbHtml.GetAsString())

Dim success As Boolean = mailman.SendEmail(email)
If (success <> True) Then
    Debug.WriteLine(mailman.LastErrorText)
Else
    Debug.WriteLine("Mail Sent!")
End If