Great ;)

Problem solved. But i will test it on a new Ubuntu installation and figure out, what the problem is. 

Hve a nice day

Greetings 

Mike

Mi Mär 25 2026 01:32:16 UTC von alanlau Betreff: Re: New Citadel Installation not receiving mail nor response to external SMTP check

Hi Mike,

Successfully tested on Debian 13 and works like a charm.

Therefore I concluded it MUST be ubuntu's problem, or at least its on OS setting I'm not awared of.

I had prepared a native Debian 13 and using native installation by Easyinstall script.

Tue Mar 24 2026 05:38:54 PM UTC from Motobike Subject: Re: New Citadel Installation not receiving mail nor response to external SMTP check

Hi, its not that different to Ubuntu. Its the same base. 

So i think you dont have any problems to use it. How you install citadel on Ubuntu ? As a Docker Container or nativ ? you need to chown right on Ubuntu. 

The problem is not the OS itself. 

 

But if you can telnet citdael on port 25, it might be not a OS problem. i think its a administrativ right problem for citadel or the service.

you checked the status for citadel service ?

 

systemctl status citadel.service

 

Greetings Mike

 

D

I just writing here to report that my previous new Debian installation for Citadel wasn't working as expected, with same result that unable to receive external message nor response to MXTOOLBOX server test.

When I first preparing it I used another IP for both internal and external network and it works fine.  However when I change back to my original email domain's IP address it just not responding.

Even though it's not responding to MXTOOLBOX server test, it does response to telnet port 25.  

I had no choice but put the old server back and everything fine again.  I am still investigating the reason....

Hi Alan,

please try to figure out, whats going on.

Check Services on Ports:

ss -tulpn

Also you can swtich port inside Citadel to antoher MTA Port and check, if you can Telnet it. Do you import Setting from an old Citadel installation ? 

I checked lates Debian and Ubuntu Version with Citadel and had no problems. 

My Settings:

Mo Mär 30 2026 01:25:28 UTC von alanlau Betreff: Re: New Citadel Installation not receiving mail nor response to external SMTP check

I just writing here to report that my previous new Debian installation for Citadel wasn't working as expected, with same result that unable to receive external message nor response to MXTOOLBOX server test.

When I first preparing it I used another IP for both internal and external network and it works fine.  However when I change back to my original email domain's IP address it just not responding.

Even though it's not responding to MXTOOLBOX server test, it does response to telnet port 25.  

I had no choice but put the old server back and everything fine again.  I am still investigating the reason....

Hi Mike,

My server is running on VMs.  Since my new server is not working last week, I had reinstate the old server VM back to use the original Domain and IP, and I had the new server VM continue running but use another IP.

If running on another IP, it response to MXTOOLBOX mail server test.

If put the new server back to my original IP, it doesn't.

Had used your command to check the common ports  (24/456/587 etc) are all listening by Citadel only.

Will it be any relations to DNS setting that binded to the original old server? Such as MAC address binding?  

Mon Mar 30 2026 06:37:27 AM UTC from Motobike Subject: Re: New Citadel Installation not receiving mail nor response to external SMTP check

Hi Alan,

please try to figure out, whats going on.

 

Check Services on Ports:

ss -tulpn

Also you can swtich port inside Citadel to antoher MTA Port and check, if you can Telnet it. Do you import Setting from an old Citadel installation ? 

I checked lates Debian and Ubuntu Version with Citadel and had no problems. 

 

Sorry the previous message typo - ports 25/465/587 

Hi Alan,

i think, i need some more details about your setup. 

The DNS entrys doenst need to change. 

Your Citadel installation is on premise / selfhosted inside your own network?

If the new server have a different IP Address, maybe it wouldnt work. Do you checked your Firewall ports and port routing ? 

If you Citadel is inside your network, can you telnet from a different computer to your Citadel Server ?

For more details about your setup you can mail me if you want. Maybe there  informations not for everyones eyes, but the solution is good for all. 

Greetings 

Mike

michael@g00r00.com

Di Mär 31 2026 09:09:38 UTC von alanlau Betreff: Re: New Citadel Installation not receiving mail nor response to external SMTP check

Hi Mike,

My server is running on VMs.  Since my new server is not working last week, I had reinstate the old server VM back to use the original Domain and IP, and I had the new server VM continue running but use another IP.

If running on another IP, it response to MXTOOLBOX mail server test.

If put the new server back to my original IP, it doesn't.

Had used your command to check the common ports  (24/456/587 etc) are all listening by Citadel only.

Will it be any relations to DNS setting that binded to the original old server? Such as MAC address binding?  

 

Mon Mar 30 2026 06:37:27 AM UTC from Motobike Subject: Re: New Citadel Installation not receiving mail nor response to external SMTP check

Hi Alan,

please try to figure out, whats going on.

 

Check Services on Ports:

ss -tulpn

Also you can swtich port inside Citadel to antoher MTA Port and check, if you can Telnet it. Do you import Setting from an old Citadel installation ? 

I checked lates Debian and Ubuntu Version with Citadel and had no problems. 

 

Thanks Mike for help.

1. DNS - noted

2. Installation -- inside our own premise on VMWare host.  Host with 2 LAN card, one for LAN and another for WAN.  WAN adapter had external IP independent from LAN.

3. Since new server not working on existing Domain name and IP, it is now running simulatenously together with current server but with different LAN and WAN IP for troubleshooting

4. Telnet -- already test within own LAN as well as externally (from my home and at another office) -- both can successfully telnet port 25 of new server, on both WAN IP (24 & 28 when trying to switch).

Existing server setup: Citadel on Ubuntu 18.04 VM on VMWare, WAN IP xxx.xxx.xxx.28.  Server had been running since 2018 and having maintenence issue therefore prepared to be replaced.

New server now prepared: Citadel on Debian 13 VM on VMWare, WAN IP xxx.xxx.xxx.24.  Completely new install and not migration.  Both server on SAME vmware host with same network adapter, both LAN and WAN.

Problem: after shutdown existing server, and replace the new server to IP ending with 28, it does not receive external mail nor passing MXTOOLBOX server test.  However when placing back to IP ending with 24, MXTOOLBOX test (using IP) works.  Returning the existing server back online will have everything working fine.

Tue Mar 31 2026 10:04:57 AM UTC from Motobike Subject: Re: New Citadel Installation not receiving mail nor response to external SMTP check

Hi Alan,

 

i think, i need some more details about your setup. 

The DNS entrys doenst need to change. 

Your Citadel installation is on premise / selfhosted inside your own network?

If the new server have a different IP Address, maybe it wouldnt work. Do you checked your Firewall ports and port routing ? 

If you Citadel is inside your network, can you telnet from a different computer to your Citadel Server ?

 

For more details about your setup you can mail me if you want. Maybe there  informations not for everyones eyes, but the solution is good for all. 

 

Greetings 

Mike

michael@g00r00.com

 

 

Forget to mention both Ubutnu and Debian had no Firewall enabled.  

External IPs also running without Firewall equipment/UTM until everything had solved.