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TIdMessageEncoding

TIdMessageEncoding = (meDefault, meMIME, mePlainText)

Example​

procedure ConfigureMessageLayout(Message: TIdMessage);
begin
  Message.Encoding := meMIME;
end;

Usage​

TIdMessageEncoding controls whole-message plain-text or MIME layout and Velox's automatic choice for a mail message.

Members​

ValueOrdinalMeaning
meDefault0Let header generation choose plain text when there are no parts or MIME when parts exist.
meMIME1Generate MIME layout and set the message-parts attachment encoding to MIME.
mePlainText2Generate non-MIME/plain layout and set attachment encoding to legacy UUE unless later overridden.

Behavior and boundaries​

  • Assigning any value other than meMIME, including meDefault, immediately sets AttachmentEncoding to UUE; automatic generation can later change the layout.
  • Encoder lookup can raise after the enum field has been stored, leaving partially updated message state.
  • ClearHeader restores this property to meDefault but does not reset AttachmentEncoding; a reused message can therefore show meDefault while retaining a previous encoder selection.
  • When parts exist, unsupported part transfer encodings are normalized: MIME falls back to base64, while plain-text layout falls back to UUE.
  • With message parts present, a non-7bit/8bit/binary whole-body transfer encoding is cleared because attachments in an encoded body are unsupported.
  • On input, absence of MIME-Version selects mePlainText; its presence selects meMIME. The parser does not restore meDefault.
  • Use CharSet, ContentTransferEncoding and part ContentTransfer for representation details; do not overload this enum with those decisions.

Additional Technical Info​

TIdMessageEncoding selects the message-level layout used by TIdMessage. Despite the name, it is not a character set and is not the per-body or per-part Content-Transfer-Encoding.

meDefault is stateful automatic selection during header generation: no message parts changes the message to mePlainText; any message part changes it to meMIME. The property no longer remains meDefault after that decision.

Related Code Library entries

External references

Created 2026-07-15