PowerShell

Convert a MIME Entity to multipart/alternative

Demonstrates the Chilkat Mime.ConvertToMultipartAlt method, which wraps the current entity in a new outer multipart/alternative, making the original the first child. It takes no arguments.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: Use this to add an alternate rendering to an existing message — for example, promoting a plain-text message so an HTML version can be added alongside it. The original content becomes the first (least-preferred) alternative, and you append the richer representation after it. As with the mixed conversion, message-level headers move to the new outer entity.

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Add-Type -Path "C:\chilkat\ChilkatDotNet47-x64\ChilkatDotNet47.dll"

$success = $false

$mime = New-Object Chilkat.Mime
$success = $mime.LoadMimeFile("qa_data/message.eml")
if ($success -eq $false) {
    $($mime.LastErrorText)
    exit
}

#  Wrap the current entity in a new outer multipart/alternative entity.  The original entity
#  becomes the first child, ready for an alternate representation to be added.
$success = $mime.ConvertToMultipartAlt()
if ($success -eq $false) {
    $($mime.LastErrorText)
    exit
}

#  Add an alternative representation of the same content.
$htmlPart = New-Object Chilkat.Mime
$success = $htmlPart.SetBodyFromHtml("<html><body>HTML alternative.</body></html>")
if ($success -eq $false) {
    $($htmlPart.LastErrorText)
    exit
}

$success = $mime.AppendPart($htmlPart)
if ($success -eq $false) {
    $($mime.LastErrorText)
    exit
}

$("Number of parts: " + $mime.NumParts)