kumomta/docs/reference/header/value.md

value

local value = header.value

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

Depending on the header name, returns one of the structured representations of the header value.

If there is no defined header name and structured representation, the fallback behavior is to return the same value that you'd see if you accessed header.unstructured.

!!! note For the sake of forwards compatibility, it is possible that we will add support for names and structured representations in future versions. In that scenario, if you were using header.value and relying on it returning the same value as header.unstructured then your logic may be broken by upgrading.

With that in mind, we recommend that you explicitly use `header.unstructured`
in your code for headers that are not included in the table below, rather
than relying on the fallback behavior.

Supported Header Names and Types

If the Since column is blank, it is assumed to be since the inception of header.value, which is the version shown at the top of this page.

Name	Equivalent field accessor	Since
Authentication-Results	authentication_results
Bcc	address_list
Cc	address_list
Comments	unstructured
Content-Disposition	mime_params
Content-Id	message_id
Content-Transfer-Encoding	mime_params
Content-Type	mime_params
From	mailbox_list
Message-ID	message_id
Mime-Version	unstructured
References	message_id_list
Reply-To	address_list
Resent-Bcc	address_list
Resent-Cc	address_list
Resent-From	mailbox_list
Resent-Sender	mailbox
Resent-To	address_list
Sender	mailbox
Subject	unstructured
To	address_list