Can't send mails

My eM Client fails when I try to send an email.
Under Account>Diagnostics>Diagnose the SMTP answers: “Server not responding”. When I click the “Fix”, it answers:“Settings has been fixed”, but nothing seems to be fixed on the SMTP settings-tap and I still can’t send emails!
What to do?
eM Client=6.0.19714.0

Hi, what email service provider do you use? Please make screenshot (or write me here) your SMTP settings (port and security).