[vox-tech] Anyone running a mail server on a dynamic IP?

[Rod Roark]

On Tuesday 22 June 2004 12:06 am, Brian Lavender wrote:
> On Wed, Jun 16, 2004 at 10:15:18PM -0700, Rod Roark wrote:
> > Seems like most of the spam that I (and thus LUGOD) are not
> > successfully filtering out these days is from dynamic IPs -
> > dialup, cable modem, and dynamic DSL.
> > 
> > So I'm wondering if it's reasonable to refuse mail from
> > servers that connect directly from a dynamic IP.  Is anyone
> > here running such a server?  And if you are, are you finding
> > that many sites are refusing your mail?
> > 
> > Please reply off-list unless you think that what you have to
> > say is of general interest.  Also if you're not sure if your
> > IP is considered dynamic, you can check it at
> > "http://www.dnsbl.us.sorbs.net/cgi-bin/lookup?IP=".
> 
> Well, consider this. You have a valid send who is sending you email from
> a dynamic IP. You would want to receive that email, right?!!
> 
> The answer lies in SpamAssassin. I believe it scores on this blacklist.
> SpamAssassin has been 100% effective with over 300+ spams in the last
> 24+ hours!

100% is astounding.  My experience with SA was nothing like
that.  But it has a huge number of options; how do you have
it configured?  What about false positives?  Any idea how
many unique spam sources are represented in those 300
messages?

> The next question is, do you want to process this email? I 
> don't. That's why I have been testing SA-Exim. If it gets flagrant
> spam from an IP, it can put in a temporary reject. Or, it can put in a
> permanent reject. Or....  if it's really bad spam, you can teergrub it.
> Or, say I do have a sender who does use mail server on a dynamic IP. I
> can whitelist him and get his email.
> 
> I am doing a talk on integrating SpamAssassin at the SMTP layer. The
> implementation is SA-Exim. http://www.saclug.org/

Well I use Postfix.  I believe the rough equivalent with
that would be something like amavisd-new which runs
SpamAssassin "internally", using the "before queue content
filter" which Postfix introduced with release 2.1.  I don't
know anyone who has tried this combination yet.

-- Rod