I was able to configure mandrillapp.
But trying to configure a different SMTP server does not work. Tried to configure Amazon SES while waiting for confirmation to send. I tried to configure from mail.ru or Yandex.ru, nothing happens, errors or what not. On the page is simply reloaded, meaning I will not get on the message page, check your email, etc
And few minute ago I get this error : "SECURITY PROBLEM: insecure server advertised AUTH=PLAIN" - when I tried to configure bounce server.
Your first issue, you should at least get a message telling you what is wrong, if it doesn't, then something is wrong, maybe you have some PHP functions disabled, Just login in Backend -> Misc -> PHP Info and look for disable_functions and paste here its value.