Question Hot wo block smtp port (25) with firewall

[Mark387]

Hi,
I want to block the smtp port with the plesk firewall admin, because I want to prevent any incoming connections to the SMTP server. The default rule "SMTP (submission port) server Deny incoming from all" is turned on, but obviously the port is not blocked because I can still connect via Telnet at port 25. Even if I manually add a rule to block port 25 for all incoming connections, the port is still open. What can be the reason for this?

I am using Plesk 12.0.18 Update #103 on Ubuntu 14.04.5 LTS

 

[danielkaluuya007786]

• Outgoing mail connections via 25 port are not possible:
  
  # telnet mail.example2.com 25
  Trying 203.0.113.2...
  telnet: connect to address 203.0.113.2: Connection timed out
  Trying 2001:db8:f61:a1ff:0:0:0:80... telnet: connect to address 2001:db8:f61:a1ff:0:0:0:80 Network is unreachable.