SMTP Connection Refused

[Ki Song]

I am running Fedora Core 4 using Postfix as my mail server.

When I send/receive e-mail messages from an outside client (yahoomail,
gmail, hotmail, etc.), the messages are delivered properly.

However, when I send a message to a different e-mail server in house
(store.knifecenter.com), it says the connection is refused. Here is the
exact message that is returned in the postfix maillog:

connect to store.knifecenter.com[70.88.225.6]: Connection refused (port 25)
D7C9C3572A1: to=<listserv(a)store.knifecenter.com>, relay=none, delay=0,
status=deferred (connect to store.knifecenter.com[70.88.225.6]: Connection
refused)
disconnect from unknown[10.1.10.19]

What is going on? Any ideas?

[Robin Mordasiewicz]

On Wed, 2 Nov 2005, Ki Song wrote:

>  However, when I send a message to a different e-mail server in house
>  (store.knifecenter.com), it says the connection is refused. Here is the
>  exact message that is returned in the postfix maillog:
>
>  connect to store.knifecenter.com[70.88.225.6]: Connection refused (port 25)
>  D7C9C3572A1: to=<listserv(a)store.knifecenter.com>, relay=none, delay=0,
>  status=deferred (connect to store.knifecenter.com[70.88.225.6]: Connection
>  refused)
>  disconnect from unknown[10.1.10.19]
>
>  What is going on? Any ideas? 
It looks like you will either need to set up an SNAT on your firewall, or 
use a split DNS. The problem is that you are probably trying to connect to 
store.knifecenter.com, which is really a box in your DMZ or whatever, 
but the box on the inside is on a private LAN such as 10.1.10.20.

Telnet is your friend when troubleshooting mail servers.

ie.

telnet 10.1.10.19 25

you will then be able to issue commands directly to the mail server such 
as the following after a successfuly telnet to port 25 of the server.

helo mail.myserver.com
mail from: me(a)domain.com
rcpt to: listserv(a)store.knifecenter.com
data
this is a test
.

[David-Paul Niner]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Ki Song wrote:
>  I am running Fedora Core 4 using Postfix as my mail server.
>  
>  When I send/receive e-mail messages from an outside client (yahoomail,
>  gmail, hotmail, etc.), the messages are delivered properly.
>  
>  However, when I send a message to a different e-mail server in house
>  (store.knifecenter.com), it says the connection is refused. Here is the
>  exact message that is returned in the postfix maillog:
>  
>  connect to store.knifecenter.com[70.88.225.6]: Connection refused (port 25)
>  D7C9C3572A1: to=<listserv(a)store.knifecenter.com>, relay=none, delay=0,
>  status=deferred (connect to store.knifecenter.com[70.88.225.6]: Connection
>  refused)
>  disconnect from unknown[10.1.10.19]
>  
>  What is going on? Any ideas?
>   
>   
Looks like you're trying to connect to a NAT'd public IP address from a
private internal address.

I would suggest one of the following options:

1.   Set up an "internal" dns server, or configure your DNS server to
support views so that all internal clients see the private rather than
the public ip address of the mail server

2.  Push out a static hosts file to each client machine with a host
entry for store.knifecenter.com that points to the private address of
your postfix box.

That should be enough to get you started.

You can learn more about views in BIND 9 here:
http://sysadmin.oreilly.com/news/views_0501.html

As far as pushing out the hosts file, you should be able to script that
action.

Let me know if I can be of any further assistance,
David-Paul Niner, RHCE
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