I tried setting the connection to SSL with port 25. Now I see two
connects in the maillog but it still doesn't work to send the mail.
What confuses me is that Thunderbird is able to establish a connection
using SSL on port 465 when connecting to the Freemail provider GMX but
not using SSL on port 465 with my mail server configuration. Otherwise
is Outlook and Outlook Express able to connect to my mail server
configuration using SSL on port 465 so it seems like there's a
difference in how my mail server handles Outlook or Outlook Express
connections and Thunderbird connections when both using SSL on port
465.