kumomta/docs/reference/mimepart/replace_body.md

replace_body

mimepart:replace_body(CONTENT, OPTIONAL_CONTENT_TYPE)

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

This method allows you to change the body portion of the mimepart, optionally changing the Content-Type in the process.

CONTENT must be a lua string (either UTF-8 or binary) representing the actual content you want to assign; mimepart:replace_body will select and apply appropriate transfer encoding to the mime part.

OPTIONAL_CONTENT_TYPE is an optional string specifying the content type. If omitted, if the part already has a content type, that content type will be preserved. Otherwise, if there is no content type, a default content type will be selected based on the binary or text nature of CONTENT.

The example below unilaterally changes the body of a mime part to plain text:

mimepart:replace_body('changed content', 'text/plain')

See also:

• mimepart.body