Trouble setting up a mail server with dynamic dns

you need ddns? does your isp block p 25?

No router, DNS will be the router, mail server, dns server, dhcp server, domain controller. The modem is straight to the NS server.

Make port forward on modem to 25 port of Nethserver

did you tried to telnet port 25? Are you trying to access the server from
internal or external network? to which ip is you client resolving?

My modem is briged mode.

Send us the dns so we can try to connect to pop or smtp and

Seems not resolvable

[ ~]$ telnet 25 No address associated with name
[ ~]$ ping
ping: unknown host
[ ~]$
[ ~]$ ping
ping: unknown host
[ ~]$ dig

; <<>> DiG 9.4.1 <<>>
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 41696
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

; IN A

;; AUTHORITY SECTION: 1752 IN SOA 1456163364 3600 600 604800 10800

;; Query time: 38 msec
;; WHEN: Wed Feb 24 16:54:01 2016
;; MSG SIZE rcvd: 93

[ ~]$ nslookup

Non-authoritative answer:
*** Can’t find No answer

Seems that you don’t have your dns set correctly, and you might need to
open those ports in the firewall of the ns.

[ ~]$ ping
PING ( 56(84) bytes of data.
64 bytes from ( icmp_seq=1 ttl=54
time=110 ms
64 bytes from ( icmp_seq=2 ttl=54
time=104 ms
64 bytes from ( icmp_seq=3 ttl=54
time=98.4 ms
64 bytes from ( icmp_seq=4 ttl=54
time=98.5 ms

and you DO need to open those ports in the firewall of the ns

Or your ISP is blocking them.

>telnet 25
Connecting To not open connection to the host, on port 25:
 Connect failed


Oh sorry, in this moment I am upgrading the NS server. It is down. Sorry man.

This conversation has some trouble getting started properly.
@lvicentini, please provide ALL relevant information. We can not help you properly if we have t guess what you tried to configure and what the result of that was.

I understand you want to use Zoneedit as a dyndns service because you have a dynamic IP address from your internet provider.
You have registered a domain name: and want to use that for the webservices on your home internet connection.

First thing we need to know is: do you have your domain already registered with zoneedit?
When you have registered your domain with zoneedit, you can create records for it.

If you want to use the mail server options, make sure your provider has not blocked port 25 for mail. Many consumer internet lines are blocked for mailservers. Alternatively use the smtp smarthost of you internetprovider.

So please, provide all the info first. Our glass bowl is a bit foggy… :frowning:


I can reach a NethServer login page on port 980 of, but email ports seem closed (I can’t reach port 25 or 587).
Port 465 is open.
I think that Claro blocks smtp:

Okay @robb, I am sending information relating to the ZoneEdit. Thanks for your help.
Registration Domain Screen.

Dynamic Domain Screen.

CNAME records Screen.

MX records Screen.

Thank you for the info. From @filippo_carletti we already saw that the DNS redirection is working. But the smtp part (port 25) not since that port is not open.
Did you open smtp port in NS firewall?
Did you ask your provider if private smtp is allowed? If not, you should use the smtp smarthost to send your emails.

But not for mail:

[eddie@NethServer ~]$ ping
ping: unknown host
[eddie@NethServer ~]$ ping
PING ( 56(84) bytes of data.
64 bytes from ( icmp_seq=1 ttl=46 time=205 ms

For that to work, there needs to be a CNAME entry for

But the bigger issue appears to be that port 25 is blocked.


I changed of provider, really my old provider have these ports blocked. The new installation will tomorrow, 02/26/2016 10:00am in Brazil. Thanks a lot for all and see you later.

1 Like

Good, keep us in touch :slight_smile:

This is my first post, so please tell me if this is off topic!

I have had my own mail server for over 20 years, and have switched ISP’s because of port 25 blocking. Unfortunately, all the ISP’s in my area are blocking port 25 because of spammers setting up their own private mail servers on their network. So, last summer when my ISP (the last of the ISP’s port 25 blocking), I had to make a change to an external host for my email, but I did not want to pay for an email server (most are crazy expensive).

I ended up searching for a free solution that would give me about 5-10 email address’ for my domain. I finally found a company called Zoho (it’s an Indian company) and they have a free service that gives you 10 emails with a 2GB per email account. I’ve been using them for about six months now and it’s a great alternative, if you have no other options!

In this case, another solution may be setting up a cheap VPS, what do you think?

Btw, thanks for posting and welcome aboard! Would you mind to say something about you?

2 posts were split to a new topic: Having trouble setting up the MX relay