SSL secured mail ports are filtered after enabling Plesk firewall

Symptoms

• Windows firewall is disabled

• No additional firewalls exist in network infrastructure

• MailEnable mail server is installed

• Ports for SMTPS, IMAPS, POP3S connections are closed:

  # nmap 203.0.113.2 -p465,587,993,995

  PORT STATE SERVICE
  465/tcp closed smtps
  587/tcp closed submission
  993/tcp closed imaps
  995/tcp closed pop3s

• When Plesk Firewall at Plesk > Tools & Settings > Firewall is enabled, ports become filtered:

  # nmap 203.0.113.2 -p465,587,993,995

  PORT STATE SERVICE
  465/tcp filtered smtps
  587/tcp filtered submission
  993/tcp filtered imaps
  995/tcp filtered pop3s

Cause

Additional secured ports are not configured in MailEnable.

Resolution

1. Connect to the server via RDP
2. Launch MailEnable Management Console from Start menu
3. Expand MailEnable Management > Servers > Localhost > Services and Connectors
4. Right-click on SMTP > Properties > Inbound > Settings (Port Settings)
5. Enable the option Listen on alternate port:
   
6. Right click on IMAP/POP3 > Properties > General
7. Enable the option Also listen on alternative ports: