mettle sendportal APIv1 Webhooks mailjet missing authentication

A vulnerability has been found in mettle sendportal up to 3.0.1. This issue affects the function sendgrid/postmark/postal/mailjet of the component APIv1 Webhooks. The manipulation leads to missing authentication. The attack is possible to be carried out remotely. The exploit has been disclosed to the public and may be used. The project was informed of the problem early through an issue report but has not responded yet.