[stunnel-users] Connection setup for STARTTLS vs. SSL/TLS for POP3/SMTP mail servers?

In stunnels *.conf file I can specify the mail server name and the port for a connection. How can I tell stunnel to use STARTTLS as connect type? How can I tell stunnel to use SSL/TLS as connect type? Does stunnel support both connect types at all or only one? Is the connect type for SMTP completely determined by port e.g.: STARTTLS over port 587 and SSL/TLS over port 465 or can both connect types use both ports? Assume I do not get the supported connect type information from my webhoster: How can I find it out from my (client) side? What are there error messages? Ben