make it possible to send webhooks without attachments
Under the documentation for "Tracking Failures," there's a notation about the parameters included in the POST request that includes the following:
attachment-x attached file (‘x’ stands for number of the attachment). Attachments are included if the recipient ESP includes them in the bounce message. They are handled as file uploads, encoded as multipart/form-data.
I don't know what kind of attachments might be included in such a situation, but I would like to avoid sending any attachments in the POST request because that will only waste server resources and potentially interfere with other requests hitting my servers.