VB.NET - Convert email to HTML¶

Imports System.Collections
Imports System.Text
Imports System.Text.RegularExpressions
Imports System.IO
Imports EAGetMail 'imports EAGetMail namespace

Module Module1

    Private Function _formatHtmlTag(ByVal src As String) As String
        src = src.Replace(">", ">")
        src = src.Replace("<", "&lt;")
        Return src
    End Function

    Private Function _formatAddresses(ByVal addresses As MailAddress(), ByVal prefix As String) As String
        If addresses.Length = 0 Then
            Return ""
        End If

        Dim buffer As StringBuilder = New StringBuilder()
        buffer.Append(String.Format("<b>{0}:</b> ", prefix))

        For i As Integer = 0 To addresses.Length - 1
            buffer.Append(_formatHtmlTag(addresses(i).ToString()))

            If i < addresses.Length - 1 Then
                buffer.Append("; ")
            End If
        Next

        buffer.Append("<br>")
        Return buffer.ToString()
    End Function

    ' We generate a html + attachment folder for every email, once the html is create,
    ' next time we don't need to parse the email again.
    Private Sub _GenerateHtmlForEmail(ByVal emlFile As String, ByVal htmlFile As String, ByVal attachmentFolder As String)
        Dim mail As Mail = New Mail("TryIt")
        mail.Load(emlFile, False)

        If mail.IsEncrypted Then
            Try
                ' This email is encrypted, we decrypt it by user default certificate.
                ' you can also use specified certificate like this
                ' cert = new Certificate()
                ' cert.Load("c:\test.pfx", "pfxpassword", Certificate.CertificateKeyLocation.CRYPT_USER_KEYSET)
                ' mail = mail.Decrypt(cert)
                mail = mail.Decrypt(Nothing)
            Catch ep As Exception
                Console.WriteLine(ep.Message)
            End Try
        End If

        If mail.IsSigned Then
            Try
                ' This email is digital signed.
                Dim signerCertificate As Certificate = mail.VerifySignature()
                Console.WriteLine("This email contains a valid digital signature.")
            Catch ep As Exception
                Console.WriteLine(ep.Message)
            End Try
        End If

        ' Decode winmail.dat (Outlook TNEF Stream) automatically.
        ' also convert RTF body to HTML body automatically
        mail.DecodeTNEF()

        Dim html As String = mail.HtmlBody
        Dim header As StringBuilder = New StringBuilder()

        header.Append("<font face=""Courier New,Arial"" size=2>")
        header.Append("<b>From:</b> " & _formatHtmlTag(mail.From.ToString()) & "<br>")

        header.Append(_formatAddresses(mail.[To], "To"))
        header.Append(_formatAddresses(mail.Cc, "Cc"))

        header.Append(String.Format("<b>Subject:</b>{0}<br>" & vbCrLf, _formatHtmlTag(mail.Subject)))

        Dim attachments As Attachment() = mail.Attachments

        If attachments.Length > 0 Then
            If Not Directory.Exists(attachmentFolder) Then
                Directory.CreateDirectory(attachmentFolder)
            End If

            header.Append("<b>Attachments:</b> ")
            For i As Integer = 0 To attachments.Length - 1
                Dim attachment As Attachment = attachments(i)
                Dim attachmentName As String = String.Format("{0}\{1}", attachmentFolder, attachment.Name)
                attachment.SaveAs(attachmentName, True)
                header.Append(String.Format("<a href=""{0}"" target=""_blank"">{1}</a> ", attachmentName, attachment.Name))

                If attachment.ContentID.Length > 0 Then
                    ' Show embedded image.
                    html = html.Replace("cid:" & attachment.ContentID, attachmentName)
                End If
            Next
        End If

        ' Change original meta header encoding to utf-8
        Dim reg As Regex = New Regex("(<meta[^>]*charset[ " & vbTab & "]*=[ " & vbTab & """]*)([^<> " & vbCrLf & """]*)", RegexOptions.Multiline Or RegexOptions.IgnoreCase)
        html = reg.Replace(html, "$1utf-8")

        If Not reg.IsMatch(html) Then
            header.Insert(0, "<meta HTTP-EQUIV=""Content-Type"" Content=""text/html; charset=utf-8"">")
        End If

        html = header.ToString() & "<hr>" & html

        Using stream As FileStream = New FileStream(htmlFile, FileMode.Create, FileAccess.Write, FileShare.None)
            Dim buffer As Byte() = Encoding.UTF8.GetBytes(html)
            stream.Write(buffer, 0, buffer.Length)
            stream.Close()
        End Using

    End Sub

    Sub ConvertMailToHtml(ByVal fileName As String)
        Try
            Dim pos As Integer = fileName.LastIndexOf(".")
            Dim attachmentFolder As String = fileName.Substring(0, pos)
            Dim htmlFile As String = fileName.Substring(0, pos) & ".htm"

            If Not File.Exists(htmlFile) Then
                ' We haven't generate the html for this email, generate it now.
                _GenerateHtmlForEmail(fileName, htmlFile, attachmentFolder)
            End If

            Console.WriteLine("Please open {0} to browse your email", htmlFile)
        Catch ep As Exception
            Console.WriteLine(ep.Message)
        End Try
    End Sub
    Sub Main()
        Try
            ConvertMailToHtml("c:\my folder\test.eml")
        Catch ex As Exception
            Console.WriteLine(ex.Message)
        End Try

    End Sub
End Module