Mail server with port-blocking ISP (Was: Re: Looking for classes and advice)

[Craig White]

On Mon, 2007-02-26 at 02:51 -0700, David Bendit wrote:
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> On Feb 25, 2007, at 9:44 PM, der.hans wrote:
> 
> > Set up and
> > run your own mail server and web server. Learn how to keep your own
> > firewall secure and how to subnet your network for servers on one  
> > side and
> > desktops on the other. If you only have two boxes, setup virtual
> > interfaces and pretend :). If you only have one box, setup virtual
> > interfaces and pretend even more.
> 
> Actually, I've been wondering about this for a while, and I've never  
> found a way to do it. Is there a way to run a mail server on a  
> standard account (non-business) with a port-blocking ISP? I'm going  
> through Cox, and they block all the fun ports (80, 25, and a bunch  
> more). I've even been able to set up postfix before, but only for  
> intra-network mail. To get mail out, I had to use a relayhost, and  
> the only way I could find to get mail in always involved a forwarder.  
> However, with the forwarder, most spam blocking measures  
> (greylisting, RBLs, etc.) were rendered useless. If you guys can  
> offer any tips, that'd be great.
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the answer is that you can't. Things like greylisting and RBL's are only
useful at the point where an SMTP server that is designated as the MX
for your domain. Whether you retrieve your email from that system via
ETRN, fetchmail or other methods, at that point, the mail has already
been accepted and thus greylisting or RBL blocks and even bouncing mail
is futile or worse.

Craig