kumomta/docs/reference/message/append_header.md

append_header

message:append_header(NAME, VALUE)

Constructs a header from NAME: VALUE and appends it to the header portion of the message.

The VALUE is taken as-is and used as the header value.

{{since('2025.12.02-67ee9e96')}}

This method now accepts an additional optional ENCODE parameter, which should be a boolean value:

message:append_header(NAME, VALUE, ENCODE)

When ENCODE is set to true then the VALUE will be encoded:

• If the header value is ascii then it will be soft wrapped at whitespace around 75 columns, and hard-wrapped regardless of whitespace at 900 columns.
• If the header value is non-ascii then it will be quoted printable encoded using RFC 2047 header encoding.