----- Original Message -----
From: "Jonas Pasche" <[EMAIL PROTECTED]>
To: "vpopmail" <[EMAIL PROTECTED]>
Sent: Sunday, March 09, 2003 9:15 PM
Subject: Re: [vchkpw] smtp filter proxy

> Hi Jesse,
> > If I don't allow email to come into my network with forged FROM
> > headers(or even forged envelope sender headers if they're relevent)
> Here's already an error in your idea - you can't reliably see if a
> sender address is forged, and therefore:

But I can. It's simple:

(If the user is NOT on one of my network IPs, OR, if the user has not POPed before 
sending SMTP, ) AND the incoming email contains
one of my internal domains in the FROM (envelope or header), then it's bogus.

Is there a problem with that?

> > how would that NOT prevent the spam from reaching my user's inboxes??
> You can't identify these with your filtering rule.
> You cleary said that your filtering rule applies to mail that uses one
> of your domains (or these of your customers) as the From address. Thus
> your definition of a forged sender is: "Every mail with a sender address
> using one of my domains, but not relayed through our mail server". That
> might a more or less proper check (personally, I'd say: less), but
> doesn't match the vast majority of mails with forged sender addresses:
> Take 10,000 spam mails you collected in your users inboxes. How many of
> them have a (forged) sender that uses one of your domains in their From
> address?
> I'd really wonder if this is more than, let's say, one, unless your spam
> situation is _totally_ different than mine and probably most others. The
> spam mails I get (and I get a lot; thankfully SpamAssassin helps me
> pre-sorting them into a different IMAP folder) are from forged
> hotmail.com, yahoo.com or aol.com addresses in most cases. As long as
> Hotmail, Yahoo and AOL aren't your customers, your filtering rule would
> match nearly nothing.
> Summary: I think your filtering rule has nearly no effects on spam
> catching, _and_ it has drawbacks to your customers that want to use
> another mail relay than yours. I'd prefer not to use it.
> Jonas

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