ContentDisposition
property ContentDisposition: string read write;
Example
procedure InspectMessageDisposition(var Value: Variant);
var
Msg: TIdMessage;
begin
Msg := Email;
if Msg = nil then Exit;
// Useful after a load/ProcessHeaders operation.
Value := Msg.ContentDisposition;
end;
Usage
ContentDisposition exposes the parsed message-level Content-Disposition value, but current generated output does not project later typed-property edits.
Additional Technical Info
ContentDisposition stores the message-level value parsed from the raw Content-Disposition header. It is a direct, unvalidated String field. ProcessHeaders replaces it from raw Headers, and ClearHeader resets it to empty.
Important output limitation
The current GenerateHeader implementation never writes this typed property back to generated headers. It begins by copying raw Headers, so an existing raw Content-Disposition line can survive for ordinary layouts, but changing this property afterwards does not update that line. For single-part MIME, generation explicitly removes the copied message-level field so the one part can emit its own disposition.
For outgoing MIME content, set ContentDisposition on the relevant TIdText or attachment part. If a true message-level field is required, manage the raw Headers/ExtraHeaders path deliberately and verify the selected layout; ExtraHeaders are appended after standard generation and can introduce duplicate fields. NoEncode writes only raw Headers, not this value.
The String can include disposition parameters such as filenames, but this setter performs no quoting, parsing, sanitization or RFC validation. Do not concatenate untrusted filenames or CR/LF-bearing text into header lines. Prefer part properties that apply the encoder's normal header formatting.
This property is therefore primarily useful for inspecting parsed state and for compatibility with native Indy code that reads it. The example only reads it and was not runtime-tested.
External references
- Velox-modified Indy:
IdMessage.pas- upstream field/parse shape; Velox source confirms the missing generation projection. - Indy upstream: part disposition output - the active output paths for text and attachment parts.
- RFC 2183 - Content-Disposition syntax and security considerations.