SMTP Error (-1): Connection to server failed

Hi there,
I was trying to set up the mail for my domain, but I haven’t been able to do so:
When I login to the roundcube with the credentials, when trying to send the composed email says:

SMTP Error (-1): Connection to server failed.

The main goal was to follow this tutorial, which I did the DNS stuff and opened ports on ufw and hestia as well. Do you have any idea why this is happening?

Check /var/log/exim/mainlog

Hi Eris,
in my case, this file/folder does not exist in my server. I’ve found cat /var/log/exim4/mainlog and many more log files in the /var/log/exim4 folder.

is the correct one…

Finally, i reinstalled the entire hestia and ubuntu vps machine. That solved the problem, but it looks like i didn’t have dovecot installed