Delphi ActiveX

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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var
success: Integer;
mime: TChilkatMime;
htmlPart: TChilkatMime;

begin
success := 0;

mime := TChilkatMime.Create(Self);
success := mime.LoadMimeFile('qa_data/message.eml');
if (success = 0) then
  begin
    Memo1.Lines.Add(mime.LastErrorText);
    Exit;
  end;

//  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 = 0) then
  begin
    Memo1.Lines.Add(mime.LastErrorText);
    Exit;
  end;

//  Add an alternative representation of the same content.
htmlPart := TChilkatMime.Create(Self);
success := htmlPart.SetBodyFromHtml('<html><body>HTML alternative.</body></html>');
if (success = 0) then
  begin
    Memo1.Lines.Add(htmlPart.LastErrorText);
    Exit;
  end;
success := mime.AppendPart(htmlPart.ControlInterface);
if (success = 0) then
  begin
    Memo1.Lines.Add(mime.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Number of parts: ' + IntToStr(mime.NumParts));