full-disclosure - [MISC] SBC Blocks Port 25

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From: sean at donelan.com (Sean Donelan)
Subject: [MISC] SBC Blocks Port 25 - No Exceptions.

Although it would be best if the SBC call center provided the
information, it appears some inaccurate information has been
provided.  I apologize for the inconvience and incorrect information.

SBC began to apply SMTP port 25 filters on Broadband and Dialup
connections using DYNAMIC IP addresses in October 2004.  This
includes both residential and businesses using DYNAMIC IP
addresses on broadband or dialup connections.  The change was
announced by SBC in the September 2004 customer newsletter and
on the SBC web site.

The SMTP port 25 filters are NOT being applied to broadband connections
using STATIC IP addresses nor to dedicated connections such as T1/T3 or
ATM/Frame-relay circuits.  A few customers with so-called "Sticky"
IP addresses may have accidently had a port 25 filter applied, but
they should now be automatically opted-out of the port 25 filter like
other customers with STATIC IP addresses.

The difference is connections using Dynamic versus Static (Sticky) IP
addresses; not business or consumer accounts.

Mail servers typically use connections with STATIC IP addresses,
and are fairly rare (except for viruses) on Dynamic IP addresses.
Mail user agents (Outlook, Eurdora, Netscape, etc) are more common
on Dynamic IP addresses.

Mail user agents using any of the following will NOT be affected by
the SMTP port 25 filters applied by SBC (or other ISPs).

   1. Your ISP's servers as a smarthost for outbound SMTP Port 25
   2. RFC 2476 Message Submission Protocol on Port 587
   3. Virtual Private Network (or PPTP) to a private mail server
   4. Web mail (Outlook Web Access and other Web mail services)

It would be nice if more mail servers and clients supported those by
default. Unfortunately most mail clients still use port 25 by default
and will require a change.  The good news is you can make those changes
anytime without waiting until the day your ISP begins to follow the
recommendations published by the Anti-Spam Technical Alliance, which
includes Microsoft, Yahoo, AOL and Earthlink.

Extremely few customers with Dynamic IP addresses operate their own
SMTP servers. SBC suggests customers first consider if they can
use any of the alternatives, in case one of the customer's computers
is ever infected by an e-mail virus in the future.

Nevertheless, those few customers which desire to send outbound
SMTP (port 25) e-mail directly from Dynamic IP address and can not
use any of the alternatives given above, may contact SBC to opt-out
of the port 25 filter on their Dynamic IP account.  The account
should be updated the same day the request is made (usually within
a few hours). The next time the DSL modem is reset, it will get
the new filter.  You may request the change before or after the
SMTP port 25 filters are implemented in your city.  Again, please
consider using one of the other alternatives first.

Be sure to give the PPPOE account ID in the opt-out request and
reset your DSL modem after the account is updated.  If you give a
different e-mail address or forget to reset the DSL modem, the
connection won't get the updated filter and it may appear as if
your account is still filtered long after the account was updated.