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MIMEBoundary

property MIMEBoundary: TIdMIMEBoundary read;

Example​

procedure ReportCurrentBoundary(var Value: Variant);
var
  Msg: TIdMessage;
begin
  Msg := Email;
  if Msg = nil then Exit;

  // Observe parser/generator state; normally do not push or pop it yourself.
  Value := Msg.MIMEBoundary.Boundary;
end;

Usage​

MIMEBoundary returns the live message-owned boundary stack used by header parsing and MIME generation, including non-obvious push, regeneration and pop side effects.

Additional Technical Info​

MIMEBoundary returns the live TIdMIMEBoundary stack owned by the message. The property cannot be replaced, but its exposed Push, Pop and Clear methods mutate the parser/generator state. Do not free the returned object or retain it beyond the message lifetime.

Boundary and ParentPart describe the stack's top entry. An empty stack reports an empty boundary and parent -1. Nested multipart processing pushes new entries at the front and pops back to parent contexts.

Automatic lifecycle​

  • ClearHeader empties the stack.
  • ProcessHeaders extracts a top-level boundary parameter and pushes it, but does not first clear existing entries. Repeated direct calls can therefore accumulate stale boundaries.
  • GenerateHeader clears the stack and generates a new top-level boundary whenever Encoding is meMIME, even if a previous header contained another value.
  • Full MIME body output pushes nested boundaries as needed and pops the stack while closing them. After ordinary full serialization, the generated stack can be empty again. Headers-only generation stops before that pop phase and can leave the generated entry present.
  • If body output starts without a boundary, it generates and pushes one as a fallback.

Manual stack edits do not update ContentType, raw Headers, generated headers or part parent indexes. A mismatched boundary can produce invalid MIME, omit parts or close the wrong nesting level. Treat the property as diagnostic unless implementing a fully source-informed parser/serializer workflow.

NoEncode bypasses MIME generation and does not use this stack. NoDecode suppresses MIME parsing of the body even though ProcessHeaders may already have pushed the header boundary.

The example reads state only. It was source-reviewed without parsing, serializing or sending a message.

External references

Created 2026-07-15