As yyou know there are two types of letting a local email client connect to remote secured SMTP server: 1.) through SSL-TLS and 2.) through STARTTLS How do I distinguish betwen these connection types in the stunnel.conf setup file? In a previous post I was told to look at the "protocol" parameter. Ok, if I specify protocol=smtp what does that mean: "Connect through SSL-TLS protocol" or "connect through STARTTLS protocol"? It seems to me that I ALWAYS have to specify "protocol=smtp" for ALL smtp-server connects. The stunnel documentation does not explain how to setup the *.conf file for each of the variants. Is this done only by port number 465 vs 587? That would mean there is a hidden configuration by convention! What if the webhoster would set up a special mail server at port 8888? Ben