ISPConfig, Linux, ubuntu 18.04, Roundcube, google platform - can´t get the e-mail server to work

I´m relatively new to server setup. I followed the guide on: https://www.howtoforge.com/tutorial...l-pureftpd-bind-postfix-doveot-and-ispconfig/

I´m using Google Cloud Compute Engine for the VM instances. Got everything to work fine. Except the part on the e-mail servers and account.

I changed the SMTP setup to port 2525, since I found out that Google blocks the port 25. The main problem is when I try to send e-mails through the test account. It show the message box "sending message..." but it never goes on. And doesn´t show any other error messages. Here´s the print screen of this part:


Anyone went through a similar problem? Or is it really impossible to set up a mail server with Google Cloud Platform infrastructure? Other tutorial to build e-mail servers using Google Cloud are also accepted.

Here´s my Google Cloud Firewall Configuration:

On ISPConfig, monitor -> server state, shows that SMTP-Server is offline. I´ve executed /etc/init.d/postfix restart in the terminal but that doesn´t seem to be it. Here are some print screens on some of the logs on ISPConfig:


Has anyone ran into this problem and has a solution for it? Thanks in advance.

 

Hi till,
Thanks for the help. I understood what you suggested. Makes sense. But as I said in the beginning of the post, I´m kind of new to server setup, so I have no idea on how I would do that. Do you think you guys would be interested on making a tutorial for this kind of situation? If so, I´d rather wait, as I´m kind of ahead the schedule with this project. Anyway, I´m going to return with the default configuration and try to follow this suggestion with some other sources on the web.

 

The point is you need port 25 for an email server to work. I think that's why @till suggest another server that have port 25 that can relay to your current server that is setup to use port 2525 (or other than port 25).