STARTTLS cannot be enforced. It will be used automatically if the benzeyen server supports it. The encryption type should be seki to ‘None/STARTTLS’ in this case. See here for an example on how to configure self signed certificates. I'm a frequent visitor at Signal Hill Lodge, the staff feels like https://www.metooo.co.uk/u/687456dfe0820c23ef54c8a7