We currently have a large client who is requiring our Exchange Server to be TLS capable. I have installed a certificate to the virtual smtp server. I have also added an smtp connector that is tls only for the clients domain. This works fine but a problem arises. Some of our other clients cannot send us mail. They get a Deferred TLS Handshake failed in an undeliverable receipt. I also have a sendmail server here that gives me the same errors. I know that tls is not installed on the sendmail box. My question is how can I allow these clients to send mail without having tls and still have tls as an option for our requesting client?