I have setup a mail server using this guide: https://www.ostechnix.com/setup-mail-server-using-postfixdovecotsquirrelmail-in-centosrhelscientific-linux-6-3-step-by-step/
The webmail allows to send emails between own users i.e. in local machine and to the other servers like gmail. But it cannot receive emails from outside world. Here is what I have in /etc/postfix/main.cf:
alias_database = hash:/etc/aliases alias_maps = hash:/etc/aliases command_directory = /usr/sbin compatibility_level = 2 daemon_directory = /usr/libexec/postfix data_directory = /var/lib/postfix debug_peer_level = 2 debugger_command = PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin ddd $daemon_directory/$process_name $process_id & sleep 5 home_mailbox = Maildir/ html_directory = no inet_interfaces = localhost inet_protocols = all mail_owner = postfix mailq_path = /usr/bin/mailq.postfix manpage_directory = /usr/share/man meta_directory = /etc/postfix mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain mydomain = domain.com myhostname = mail.domain.com mynetworks = 192.168.0.0/24, 127.0.0.0/8, [::1]/128 myorigin = $mydomain newaliases_path = /usr/bin/newaliases.postfix queue_directory = /var/spool/postfix readme_directory = /usr/share/doc/postfix/README_FILES sample_directory = /usr/share/doc/postfix/samples sendmail_path = /usr/sbin/sendmail.postfix setgid_group = postdrop shlib_directory = /usr/lib64/postfix unknown_local_recipient_reject_code = 550
Mydomain and myhostname is fake though. Also our ISP shouldn't block any inbound SMTP connections on port 25, but we have to double check that in a meantime. Please, advise!
Enabled firewalld service once again and opened the mentioned ports. Now this error appears when trying to send an email on squirrelmail:
Connection refused 111 Can't open SMTP stream.