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TIdMessage

TIdMessage = class(TComponent)

Example​

procedure ReadCurrentSubject(var Value: Variant);
var
  Message: TIdMessage;
begin
  Message := Email;
  if Message <> nil then
    Value := Message.Subject
  else
    Value := '';
end;

Usage​

TIdMessage represents the current mutable Internet message, owning its headers, addresses, preamble, MIME parts and boundary state across parsing and generation.

Additional Technical Info​

TIdMessage is the mutable message model used by Velox mail-processing scripts. Native Indy derives it from TIdBaseComponent; the PascalScript importer deliberately presents TComponent as its ancestor. The class combines two representations that are synchronized only by explicit methods:

  • the registered-but-ungenerated Headers property holds raw message header lines.
  • typed properties such as Subject, recipients, ContentType and Date hold parsed/editable state.
  • ProcessHeaders projects raw headers into typed properties.
  • GenerateHeader builds output headers from the typed state, retained raw headers and the registered-but-ungenerated ExtraHeaders property.

The normal script entry point is Email. It returns the message for the current action or nil when no email is assigned. Velox deliberately resolves the current instance each time because transports replace it between executions. Treat the result as borrowed: do not free it and do not cache it across records, actions, events or script executions. The importer registers no TIdMessage-specific constructor; if an available inherited constructor is deliberately used, that separate instance is caller-owned and must be freed. Most integration scripts should use Email.

The message owns its Body/NewsGroups string lists, address items/lists, raw and generated header lists, MessageParts collection and MIMEBoundary stack. Getters return borrowed child objects; clearing/removing content or destroying/replacing the message invalidates affected references.

Clear resets the main header/body model but deliberately retains some configuration and state. AddHeader appends raw text only. Load/save methods synchronously parse/serialize the object and are documented separately.

Several methods mutate more state than their names might suggest. Header generation recounts parts, resolves default encoding, normalizes transfer encodings, creates a new MIME boundary, infers ContentType and replaces generated-header state. Header processing can replace address lists, normalize values, change attachment encoder selection and accumulate boundary entries if called repeatedly without clearing.

The object and every owned collection are mutable and unsynchronized. Do not share one instance between threads or mutate it while a transport is parsing/sending. Operations are not transactional; exceptions can leave partially reset, parsed or generated state.

The source-reviewed example safely reads the current borrowed object and was not runtime-tested.

External references

Created 2026-07-15