----- 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 > > >
