Sogo Mail Server ISP blocks port 25

Hey guys,

Seeking support on mail server.

I have a nethserver working as domain controller.
Lets say:
External domain:
Domain controller:
Email server:
Wordpress for my http website.

Then i have SOGo as email server. My isp blocks port 25.

Im able to send email internally but not to the outside. Also wont receive any email.

MX record + autodiscover dns records are created. Im able to add an account into outlook.

Does anyone know what am i doing wrong?

If the ISP blocks port 25 you have to use a smarthost:

You may have a look at /var/log/maillog to check why mails are not sent/received.

To configure the smarthost:
IP: <= local ip from my mail server
username password from an admin user
port: 2525

Is this the right configuration?

Log show connection refused:

Apr 21 19:24:17 server postfix/smtp[33453]: 064164164DC7: to=<>, relay=none, delay=2102, delays=2102/0.04/0/0, dsn=4.4.1, status=deferred (connect to[]:2525: Connection refused)

Would you please explain this sentence? Outgoing? Incoming? On the server? Or on a public/internet client?
25 is a standard port for every public mail server… Probably this block could kill the server availability.

Hi pike,

Im a home user. My isp has a policy that all traffic on port 25 will be blocked. This means there is no way i can open the port 25.

Hi FabioRocha,

The best way will be to change ISP.

See They do not block ports.


1 Like

They appear to be a domain registrar and web host–how would they help OP with port 25 being blocked at his home?

I changed the port from postfix to 2525 and configure the smarthost on port 2525. But now the log show a loop.

Hi danb35,

You are right, my mistake…


You could, in theory, work around a restriction that outbound traffic on port 25 is blocked, generally by using a smarthost. But if inbound traffic on port 25 is also blocked, and you can’t convince your ISP to unblock it (perhaps by changing to a business plan), you aren’t going to be able to have an Internet mail server at home. Period. It just isn’t going to work, as port 25 is what the rest of the internet is going to try to reach.

Suggest you consider installing Neth in a remote VPS–I’ve been satisfied with Contabo, and their prices seem pretty reasonable.


Thank you danb35.

Not a positive outcome for my problem but this is the answer i was looking for.

Appreciate all the help.