Sending Email To The Internet

[Steve Caum <st...@caumfamily.com>]

A new situation that has developed that may affect people's ability to
send mail to the internet from any mail server, including James, if the
mail server is running on a host with a dynamic IP.  Now, I am
absolutely NOT an authority on this subject, and I've only learned of
this situation in the past few days.  I am confident others of you are
far more knowledgable, and provide much greater detail to interested
readers.  

Ordinary residential broadband providers almost always assign IP
addresses to their customers using DHCP, also known as 'dynamic IP
assignment'.  One of the common techniques used by 'spammers' is to set
up mail servers using residential broadband accounts, based on dynamic
IP.  There is apparently no way for SMTP servers to know if a mail
server is connecting via a static or dynamic IP address; and, since
dynamic IP's are constantly being reassigned, it is very hard to track
down who the offender was.

The 'Mail Abuse Prevention System' (MAPS) has established a database of
known spammers.  Mail servers can check received mail against the MAPS
database and reject it as spam if it is listed.  Until now, the most
common way for a mail server to get on this list was by allowing
themselves to operate as an open relay (i.e. no SMTP authentication).
Recently, a number of broadband ISP's have gotten together and compiled
lists of all IP addresses which are assigned dynamically.  Apparently,
these lists are being mass-inserted into the MAPS database, to help
further reduce the likelihood of spammers using the ISP's services for
spam.

The problem is, if you are a SOHO, or a hobbiest, operating through a
dynamic IP, it is very likely that much of the mail sent from your mail
server may be rejected.  So, if you are having trouble sending mail
through your mail server, this is a possible reason.  MAPS has published
some instructions on how to deal with this situation
(www.mail-abuse.org/dul/).

There are various solutions that range from changing the SMTP settings
of your mail client to setting up a 'smart host' on your mail server.
The purpose for this message was not to explain solutions, but to enlist
conversation.  Perhaps some of the JAMES guru's can explain how to
configure the SMTP mailet to handle this.

Sorry I was so long-winded.

Hope this is useful to someone :-)





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RE: Sending Email To The Internet

["Noel J. Bergman" <no...@devtech.com>]

> A new situation that has developed that may affect people's ability to
> send mail to the internet from any mail server, including James, if the
> mail server is running on a host with a dynamic IP.

DNS block lists have been around for years, and the DUL ("dial-up list") is
not new.  See http://relays.osirusoft.com/faq.html#_Toc533558164, for
example.  Another example, would be:
http://www.five-ten-sg.com/blackhole.php?ip=24.88.16.47.

> Apparently, these lists are being mass-inserted into the MAPS database,
> to help further reduce the likelihood of spammers using the ISP's
> services for spam.

That MAPS DUL zone has existed for years.  The end-user instructions page
was last updated in 2001.

If you are in a DHCP pool, the <gateway> element on RemoteDelivery should be
set to your upstream provider's SMTP server or other suitable relay.

	--- Noel


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