comcast blocking smtp25

[richb at pioneer.ci.net (Rich Braun)]

On Thu, Jul 14, 2005 at 11:48:09PM -0400, David Hummel wrote:
>> I don't see any reason not to use the smart host, which solves
>> both problems.

Jeff Kinz <jkinz at kinz.org> wrote:
> The smart host helps a lot, but unfortunately, Comcast has their own
> set of stupidities.
> Comcast limits outgoing email to 20 addresses  per email and
> something less than 300 per day.

At least from my home in Cambridge, Comcast is not blocking port 25 in either
direction.  But my netblock does appear in one of the third-party block-lists,
SORBS, which is used by a lot of sites' anti-spam filters.  (You can plug your
own IP address into the multi-RBL checker at http://rbls.org to see if you're
in any block-lists.)

I can see a whole *lot* of reasons to avoid using the smart-host supplied by
an ISP whose primary business is to sell you connectivity.  Comcast and its
ilk do not earn a penny providing you with a reliable, secure email service;
in fact it costs them a lot of money, manpower and aggravation to keep the
"smart" host running at all.  If you send all your mail out through a
poorly-maintained server (aka single point of failure), you can expect
occasional reliability problems; periodic acceptable-use policy updates that
force you to change something; and security holes a mile wide that could
enable unauthorized users or government officials to snoop on your email.

I just plain won't do it.

So when SORBS picked up my network address for selective spam enforcement,
what I did was search around for a reliable SMTP relay provider.  I also
reconfigured my system to use exim (most use Postfix) instead of sendmail. 
The results are very pleasing.

The one I chose is operated by dyndns.com, at a cost of $15/year for the
volume of mail that I send.  I configured my outbound rules to make direct
SMTP connections to certain sites to which I send a lot of mail and which
don't try to screen out my IP address, and the rest of my mail via the relay
service.

-rich