Issue You cannot send emails from Plesk because outbound connections on TCP port 25 is blocked.

[bernhardh86]

Server operating system version

Ubuntu 20.04.6 LTS

Plesk version and microupdate number

18.0.56

I get the following error on the mail settings page.

You cannot send emails from Plesk because outbound connections on TCP port 25 is blocked. Check the firewall settings or contact your hosting provider. If you are sure that the ports are already open, Plesk can recheck them.
Start the recheck

I checked the linked article (https://support.plesk.com/hc/en-us/...to-receive-or-send-e-mails-port-25-is-blocked) which focuses on AWS and Azure, so it isn't really helpfull, since I use none of them.

I am using plesk firewall, but there Port 25 is open (I think so):


Connecting to Port 25 over telnet works:

telnet mydomain.xxx 25
Trying 1.2.3.4...
Connected to mydomain.xxx.

What is missing?

 

[Kaspar]

By default port 25 is open in the Plesk firewall for both incoming and outgoing traffic. However, often hosting providers or datacenters restrict the use of port 25. Contact your provider to ask them if they have any restriction on port 25.

 

[bernhardh86]

I read that, but in that case: Why is telnet working?

 

[Kaspar]

Are you using Telnet to connect to your server from a different computer? And are you able to make an telnet connection from your server to another server (i.e an outbound connection)?

 

[bernhardh86]

Ah.. My fault. I tried to connect from my computer to the server and from the server to the same ip . Connecting other servers do not work.
Thanks!

 

[Peter Debik]

Just opening the port for "outgoing" still does not allow incoming traffic, so a telnet connect on 25 is not possible.
Normally you do not need to set anything in the Plesk Firewall for the port at all. If the port is closed, it is mostly due to a firewall in front of your server, at your provider.

 

[jlocana]

Just opening the port for "outgoing" still does not allow incoming traffic, so a telnet connect on 25 is not possible.
Normally you do not need to set anything in the Plesk Firewall for the port at all. If the port is closed, it is mostly due to a firewall in front of your server, at your provider.

Hola Peter

Good to see you again! I open the port 25 in the ionos.com firewall for vps. But still having issue with the port 25 for creating the mail server. I did the telnet:

C:\Users\User>telnet 24.45......... 25
Connecting To 24.45....... Could not open connection to the host, on port 25: Connect failed

Look like the port 25 ionos is block. I read the issue in Resolved - Change from SMTP port 25 to another port but was in 2017.

Theare are new update how to change the port for example 587?

Please Advice? Thanks you again!

Jose

 

[Peter Debik]

Do not change port 25 to anything else. All of the Internet transmits mail on port 25. If you change that port, your server won't be able to send or receive mails to and from other servers.

Opening the Ionos firewall is a correct step. If port 25 is open in the firewall in Plesk AND in your data center firewall, it must work. If it does not, Ionos support must help.

 

[jlocana]

Do not change port 25 to anything else. All of the Internet transmits mail on port 25. If you change that port, your server won't be able to send or receive mails to and from other servers.

Opening the Ionos firewall is a correct step. If port 25 is open in the firewall in Plesk AND in your data center firewall, it must work. If it does not, Ionos support must help.

Thank you Peter!

Best ☺

Jose

 

[jlocana]

Thank you Peter!

The port is open in the firewall but steel having issue with the mail server. Please any advice?. Thanks you

 

[jlocana]

Thanks you Peter I will call Support.

Best☺

Jose