Hi 0x0, Russell from Mailgun here. Do you have a self signed certificate by any chance? We typically downgrade a connection if we are presented with a self sign

Hi 0x0, Russell from Mailgun here. Do you have a self signed certificate by any chance? We typically downgrade a connection if we are presented with a self signed certificate. That might be what you are seeing. If you drop us an email at support [at] mailgun.com with your domain I can take a look at the specific issue we are having delivering over TLS to your domain.