Thank you all clarifiyng that my ISP is blocking port 25. This way I can insist that they are blocking port 25. Due to my weak knowledge I had to accept what they claimed that it is not blocked.
> Subject: Re: no route to host > To: postfix-users@postfix.org > Date: Sun, 29 Jul 2012 19:29:10 -0400 > From: wie...@porcupine.org > > Engin qwert: > > root@xn--hadibakalm-5ub:~# telnet 168.100.189.2 25Trying > > 168.100.189.2...telnet: Unable to connect to remote host: No route to host > > Then your ISP is blocking your outbound SMTP connections. > > I was able to connect to your server's SMTP port from 168.100.189.2 > (you should see that in your maillog file). > > > Wietse