DNS Settings For Mail Server Confusion...

[Fidster]

Hi, First timer here and Linux admin newbie... You have been warned!

Okay, I've set up an Ubuntu 11.10 server as a home project to host a small web and mail server. After many hours of trying to wrap my head around the bind config files I've finally managed to get the web server part sorted, and my DNS is playing nicely on the web according to pingability.com, but the mail server is still giving me problems. This is how my DNS zone file looks...

$ttl 7200
mydomain.com.	IN	SOA	ns.mydomain.com. root.mydomain.com. (
			1329667521
			10800
			1800
			1209600
			38400 )
mydomain.com.	IN	A	81.82.83.84		; External IP
mydomain.com.	IN	NS	ns.mydomain.com.	; Primary DNS
mydomain.com.	IN	NS	secondary-dns.co.uk.	; Secondary DNS
www*mydomain.com.	IN	A	81.82.83.84	; web server
mail.mydomain.com.	IN	A	81.82.83.84	; mail server
ns.mydomain.com.	IN	A	81.82.83.84	; name server
mydomain.com.	IN	MX	10 mail.mydomain.com.

In Webmin I can see that mail for mydomain.com is being delivered to my server, but it's being held in a Mail Queue rather than being delivered to the assigned user. The error message against each of the queued messages is;

connect to mail.mydomain.com[81.82.83.84]:25: Connection refused

As all these services are located on one machine, do I need to change something to make my SMTP connection use its internal IP address or should using the external one just loop back from my router and connect to the server on port 25?

I know port 25 is open on the server as I can telnet to it on the local network using the internal IP but not the external one. I also know that my router allows SMTP through because messages sent from elsewhere on the web are getting into the queue in the first place...

What am I missing here

[Fidster]

After much installing, re-configuring, unistalling and general hacking at various packages and their config files, I now have my mail server working.

I'd like to be more precise about exactly what the problem was, and how I fixed it, but I'm really not 100% sure. I believe it was my Postfix/Courier configuration, which had been modified by numerous failed attempts to use different server management tools in my efforts to get things set up. It took a lot messing about to purge all the unwanted modifications, but I believe my config is clean now and I'm finding Webmin very useful as a server front end.

Ultimately, what I've done is simply clean up the mess I'd made of my server and follow the instructions in the HowtoForge guide Virtual Users And Domains With Postfix, Courier, MySQL And SquirrelMail (Ubuntu 11.10), and now I'm happy again