B4X

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.

Chilkat B4X Downloads

Download Chilkat for B4X

B4X

Dim success As Boolean = False

Dim mime As ChilkatMime
mime.Initialize
success = mime.LoadMimeFile("qa_data/message.eml")
If success = False Then
    Log(mime.LastErrorText)
    Return
End If


'  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

Log("8bit/binary parts converted to base64.")
Dim mimeText As String = mime.GetMime
If mime.LastMethodSuccess = False Then
    Log(mime.LastErrorText)
    Return
End If

Log(mimeText)