Hi, I'm new with ISPConfig. It just installed in my server with mail service with postfix + dovecot. i can login with roundcube normally in web. Sending and receiving also working, i use SMTP to mailgun for sending. But i cannot connect mail server with mail client like thunderbird, with port 143, 993 or any port. Attached the netstat -tap result for the server. Any help appreciated.
Use port 587 for SMTP in your mail client and take care you use the system hostname as mail server and not a subdomain of a email domain you added, see email setup tutorial: https://www.howtoforge.com/ispconfig-email-account/ But in general, the server seems to be fine, so most likely the ports are blocked by an external firewall on the server or firewall or router in front of the server.
You are right, something blocking my connection. No wonder smtp by port 587 or 465 cannot work with mailgun. i'm using unusual specific port for SMTP and then working. i check with time nmap portquiz.net to test outgoing port and some port blocked by ISP Firewall, after uncheck the active status in ISPConfig firewall and then reboot the server, some port opened. but still imap port still blocked. any idea what was blocking the connection? i'm using linode.
i resolved the issue, using hostname always failed, but using IP ADDRESS is working. so i think it's OK now
Then most likely your hostname is not set up correctly in DNS, check that it exists as a DNS A-record and that it resolves to the correct IP address. You should check and fix that, as a non-existing hostname will likely result in email delivery failures.
i'm using external smtp service (mailgun) connected to postfix. already tested and incoming and outgoing email works fine
