kumomta/docs/reference/kumo/apply_supplemental_trace_header.md

kumo.apply_supplemental_trace_header

kumo.apply_supplemental_trace_header(msg, opt_params)

{{since('2025.10.06-5ec871ab')}}

Builds a supplemental trace header according to the optional parameters, and adds it to the message.

If opt_params is omitted or is nil, then the default params will be used. The parameters are the same as the start_esmtp_listener.trace_headers parameter value.

Example: add a default supplemental trace header

Both of these examples are equivalent:

kumo.apply_supplemental_trace_header(msg)

kumo.apply_supplemental_trace_header(msg, {
  supplemental_header = true,
  header_name = 'X-KumoRef',
  include_meta_names = {},
})