kumomta/docs/reference/message/append_text_html.md

message:append_text_html(content)

{{since('dev')}}

Identifies the primary text/html part of the message, decodes its transfer encoding, and locates the closing "</body>" or "</BODY>" tag. If the tag is found, content is inserted ahead of it. If no body tag is found, appends the content string to the part. The part is then re-transfer-encoded and the message data is updated.

This is useful for example to add a tracking pixel into the message:

umo.on('smtp_server_message_received', function(msg)
  local my_tracking_link =
    '<img src="http://10.0.0.1/img_tracker.jpg" alt="open tracking pixel">'
  msg:append_text_html(my_tracking_link)
end)

• See also:
• msg:set_data()
• msg:append_text_plain()