Postfix setup

[Gavin McCullagh]

Hi,

On Tue, 14 Aug 2007, Tom Misilo wrote:

> >1. You can connect and send mail on localhost port 25.
> >   - Postfix is at least running on localhost
> I can connect to port 25 on localhost from localhost, but sending mail
> does not work using alpine.

That's a second issue.  The upward connectivity to port 25 on other
servers.  

> Nope I cannot telnet the gmail mail host that was said earlier.

Until this works, postfix will not be able to deliver mail.  The most
likely reason for this failure, I guess, is a firewall or routing issue.
The main point is, it's a network issue, not a postfix one.

> >3. You can connect by name to port 25 from your mail server, but you get
> > "relaying denied".  This should be fixed by the "mynetworks" line above.
> >  - you should check that.
> Works now using mail.misilo in the alpine config, but mail still does
> not ever get out.

But that's for network connectivity reasons.  Postfix is now accepting mail
on all its interfaces though.

> >4. You can't telnet to port 25 from remote windows machine.
> >  - can you ping the server from the windows machine, by name and ip?
> pinging by name works and so does pinging by ip

So DNS is okay and there's basic routing between the desktop and the mail
server.  A firewall seems the most likely problem now.  That could be on
either the server or the windows machine.

> >  - what is is inet_interfaces set to in /etc/postfix/main.cf
> inet_interfaces = all
> 
> >  - what is the output of "netstat --listening --tcp"
> tcp        0      0 *:smtp                  *:*                     LISTEN
> tcp        0      0 localhost:2207          *:*                     LISTEN

Postfix is listening on all interfaces but packets are getting dropped or
blocked between your windows machine and your mail server on tcp port 25. 

On the server run:

	sudo tcpdump -i ethX port 25

changing ethX to be the interface you expect packets to arrive on (eth0
most likely?).  With the above running, redo the telnet on the windows
machine and you should see packets appearing on the tcpdump.  If the
packets arrive to the server, there is some issue (most obviously a
firewall) on the server.  If packets don't arrive, they're getting stopped
before they get to the server -- probably by a firewall on the client.

Gavin