EMBARRASSING TO THE LIST: Re: *WARNING* Your EmailAccount Will Be Closed

Marco Colombo marco at esi.it
Wed Jun 1 05:26:35 EDT 2005

On Tue, 2005-05-31 at 11:46 -0700, Jules Agee wrote:
> Kern, Tom wrote:
> > I'm subscribed to the postfix and spamassassin mailing lists and they are closed.
> > I think those 2 lists have a lot to do with email.
> > 
> > This is the only list i'm on that got hit by that german spam bot..
> > 
> > maybe you shouldn't discount every option to filter spam as "not worth the effort" or "they can get around it somehow".
> > 
> > you'd be surprised at how far just basic checks and filters can go..
> Seconded.
> info-cyrus is the only list I'm subscribed to that allows posting by
> non-subscribers. Maybe it's not a coincidence that it's also the only
> list that I get spam & viruses from on a regular basis.

This makes no sense. As I said before, it takes a close-to-zero effort
to forge headers. Subscribers-only or open, it's a matter of list
_policy_. It may have a minimal effect of reducing spam, but that's not
the point. If you want to stop spam, use a specific filter. Bypassing
the subscribers-only check is trivial.

> Spam coming through the list is more likely to bypass filters since it's
> origin is slightly obfuscated and the headers added by the list software
> add a small measure of authenticity to the message. My Bayes filter
> thinks those headers look like legit mail.

Bayesian filters do not work like that. They don't care about headers
more than any other word in the messages (they may account the fact that
a word appears in a certain header, but there's not special meaning
attached to the fact). The relevance of a word (or combination of words
if you're running something fancy), either as a spam-indicator or ham-
indicator depends on the history of _your_ setup, not on the meaning we
human beings assign to it. So it may happen that the best indicators are
NOT the usual suspects ('buy', 'viagra', ...) but something surprising.
The only thing that counts is how often a word appeared in spam and in
ham you received.

A nice reading is:

Those filters are sensitive to quick changes in message patterns. If
some german spam suddenly starts arriving, and most of the spam you
received is not german, the filters need some time to "learn" the german
words that mark spam.

Anyway this is drifting off-topic.

> It's not a major influence,
> but it does have some effect, so I think it's reasonable for the list
> admins to assume some small measure of responsibility for the junk that
> gets relayed through their system.

Again, offering email services is not part of the job of running a
mailing list. If you want to filter your email, filter at your client or
on the server you read it from. A mailing-list is just one of the source
of e-mail.

If you want to filter the water you drink, do you run all over the
planet and put a filter on every water source, or do you filter it as
soon as it enters your house? Why e-mail should be different? 

> I'm not asking for 100% accountability, and it's not that big a deal
> anyway. There will always be asshats, and there will always be a way to
> screw up a list if someone's really trying. Fortunately, those real
> asshats are relatively rare.
> All I'm saying is that it would be nice to see measures in place that
> seem to be pretty common on other lists, like restricting posting to
> subscribers. What would it hurt to implement that? Why NOT?

It's just a matter of policy. Which in turn depends on the target of the
list. A list aimed at a group of people, with some implicit commitment
to some subject, such as a SIG, a devel team, and so on is way different
from a list aimed at receiving random info or help requests, or bug
reports. If all I need is some info about a program, having to go
through the whole subscribing process (exchanging mails with majordomo,
including learning the basic syntax, or the web-mail-web cycle of
mailman) is just annoyance. I'd rather look at some other software with
easier means to access information.

This very list, while named info-cyrus, is not aimed at random users.
They'll likely complain to the mail system administrator (the guy
running cyrus software) who in turn will ask the list. If you're in
charge of running such a service, subscribing to this mailing list is
just natural.

The only annoyance of a subscriber-only filter is when it's badly
implemented, and doesn't allow you to set alternate email addresses.
It's customary (at least for me) to subscribe with a different address,
but still posting with my usual one. This allows me to implement a local
redistribution list (just an alias, actually) to reach all people
interested (i.e. the cyrus admins). Should the admins change, all I have
to touch is the local list. I have about 30 lists set up like that, and
only 2 or 3 of them require the users to manually adjust their From:
before posting.

Have a nice day,
      ____/  ____/   /
     /      /       /                   Marco Colombo
    ___/  ___  /   /                  Technical Manager
   /          /   /                      ESI s.r.l.
 _____/ _____/  _/                      Colombo at ESI.it

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