Michael Leone on 9 Sep 2004 02:01:03 -0000

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Re: [PLUG] Using fetchmail to read from an Exchange public folder for learning spam

On Wed, 2004-09-08 at 20:49, Dave Harding wrote:
> Mike Leone wrote:
> > I use postfix as a mail server, and forward everything inbound to an
> > Exchange server. The postfix server uses amavisd-new to virus and spam-scan,
> > before handing off to the Exchange server. if the spam-score is above a
> > certain number, it redirects the spam to a special Exchange email address,
> > for quarantining.
> Do you check this address personally? 

Yep; it's a public folder on an Exchange server. Think of it as a shared

>  I use a script[1] that in
> conjunction with some of my info below will allow you to report mail you
> have *verified* is UCE to Razor and Pyzor to help other poor souls
> block that particular UCE.

I don't use Razor at work, no.

> > I've found this:
> > 
> > /usr/bin/fetchmail -a -s -n -p IMAP --folder 'INBOX.Learn Spam' -m 'bash -c
> > "/usr/bin/tee >(/usr/bin/sa-learn --spam --single \ 
> >                  > /dev/null)|/usr/bin/spamc|/usr/lib/cyrus-imapd/deliver
> > $LOGNAME"' mail.hughes-family.org
> 	Ye Gods!  I expect you would need to spend a fair hunk of time 
> with the relevant manuals to figure that one out. I think this is what's
> is called a "write once" command.
> My questions for you:
> 1) Do you need to impliment this as a single command?  

Probably. I'm thinking it should be a cron job, run every so often (once
or twice a day) to suck up uncaught spam; learn it. Since I'd want
fetchmail to look in an IMAP folder, it wouldn't need to re-deliver it

> 2) Of these two options, which is the priority; minimal resource
>    overhead or maintainability? Keep in mind that it's almost certain
>    that 90%+ of the resources used in implimenting this will be SA's
>    bayesian filter.

Resource availbility doesn't really worry me, too much,

> 3) In a similar vein as the last question:
>         a) Do you presently use SA's bayesian filter?


>         Ok, assuming that you don't need to impliment this as a single 
> command, maintainablity takes precedence over a few extra resource
> stealing steps and that you can afford the cost of bayesian filtering I
> would suggest:
> 1) You setup an unprivilaged account on the postfix server
> 2) You configure fetchmail to run in daemon mode and poll that inbox
>    with the 'user' set as the above unprivilaged account (these init
>    scripts are probably available on your system already with the
>    default fetchmail install).
> 3) You Setup procmail to call SA with the appropriate actions.  For example:

1. I don't use procmail. If at all possible, I don't ever wanna have to
learn such a cryptic thing, either. :-) (at home, I use maildrop with
Courier IMAP. At work there is no IMAP or POP server; just posfix to
forward the mail)
2. The postfix server has no user accounts; it forwards all mail inward
to an Exchange server, so there are no mailboxes, actually. I suppose I
could make one.
3. Not using fetchmail at all, so no, it isn't installed.

Appreciate the script, tho.

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