Last week, the hard drive on my web/mail server ate itself. Long-story-short, I got a new drive, loaded up Mandrake 9.2 (same as the previous config), and am now having trouble with email.

I can send email around the local accounts, I can email out to external accounts and I can retrieve email from my Windows system (using Outlook Express).

What I cannot do is send email from my Windows system, or receive email from external sources. Outlook Express returns this error:
I researched the error message. Everything on it has to do with Exchange servers (not mmuch help there).

This is killing me. I've spent five days researching this. Half the people say the problem is in Postfix, the other half say it is in my HOSTS.ALLOW/DENY files. All I know is that I was running this server for over a year without any real troubles, now it's just being stubborn.

Any help would be appreciated.

Load up a portscanner or telnet to port 25 and port 110.

You probably can't because of some firewall restriction. Either on the server or on the computer you are connecting from. Also in some networks port 25 is blocked to prevent virus from spreding.

Have a look at the telnet test procedure to check if the problem is not related to your isp

http://www.tiscali.co.uk/help/email/...x800ccc0e.html

This makes the assumption that the problem is in the Windows client. The only thing that has changed is my LINUX server.

For the sake of argument, I did try the telnet test (three days ago). I can connect on 110 through OE (email is pulling down fine). I can also telnet into 110 without any trouble.

On port 25, all connections are refused. I know it isn't the Windows box because the other accounts I pull from (on other servers) are working.

If you have a problem you have to analyze your problem and use some basic tools in this case telnet.
You seem to have 2 problems:
a) you can´t forward e-mail from your OE client to a non draconisnoir.org address.
b) You are not receiving mail on your draconisnoir.org mail server from the internet.
a) Because you can sent en receive local mail to OE it looks like a relay problem.
b) could be a firewall problem or our provider is not sending, use the etrn instruction thru a telnet session at you isp to enable sending

I FOUND IT!!!!!!!!!!!!!!!!!!!

I am *so* brain-dead.

So I went out on a limb and started checking every setting.
I discovered that the Postfix server was set to accept incom,ming email from LOCALHOST only.

Set it to accept from all and now email is flowing smoothly.
Mark this one as a solution.

So now you are an open relay.

Maybe you want some authentication with that.