PowerShell

Convert 8-bit MIME Parts to Base64

Demonstrates the Chilkat Mime.Convert8Bit method, which recursively converts every part whose Content-Transfer-Encoding is 8bit or binary to base64. It takes no arguments and is a void method.

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: The original SMTP standard only guaranteed 7-bit transport, and some legacy servers still reject or mangle raw 8-bit and binary content. Converting those parts to base64 — a 7-bit-safe encoding — makes the whole message safe to relay through such systems without loss. It walks the entire tree, so a multipart message with several offending parts is fixed in one call.

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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
}

#  Recursively convert every part whose Content-Transfer-Encoding is 8bit or binary to base64.
#  This makes the MIME safe to transmit over channels that only support 7-bit text (such as some
#  legacy SMTP servers).
$mime.Convert8Bit()

$("8bit/binary parts converted to base64.")
$mimeText = $mime.GetMime()
if ($mime.LastMethodSuccess -eq $false) {
    $($mime.LastErrorText)
    exit
}

$($mimeText)