Skip to content


Since: Dev Builds Only

The functionality described in this section requires a dev build of KumoMTA. You can obtain a dev build by following the instructions in the Installation section.

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="" alt="open tracking pixel">'