Email Routing

While the junk seems to be slowing down, I've modified spamkill to kill
messages that don't have my email in To:, Cc:, or Bcc: before bringing
them down from my ISP.

How does my ISP route messages to me when my email address isn't in the
headers at all? I even get a news letter that has no headers the only
way I know what it is is based on their content. I thought that routing
info was supposed to be included in the headers.

I also understand that on a domain certain users are mandatory per RFC:
abuse, postmaster, <> and a couple of others.

I'm curious as to what <> is as I've seen it in some of the headers I
logged that I'd tossed. And am I correct in assuming that they never
should have been routed to me to start with and can safely be routed to
/dev/null.

Please keep in mind that I pay an ISP and get the email account from
them, I have a dynamic IP through them. I don't think filtering said
addresses should break anything, or is there an (ab)use of them that I'm
missing?

Any info appreciated.

TIA

Michael C.
--
(E-Mail Removed) http://mcsuper5.freeshell.org/
Registered Linux User #303915 http://counter.li.org/

"Michael C." <(E-Mail Removed)> wrote in message
news:bkkvep$2t3q1$(E-Mail Removed)

> While the junk seems to be slowing down, I've modified spamkill to
> kill messages that don't have my email in To:, Cc:, or Bcc: before
> bringing them down from my ISP.
>
> How does my ISP route messages to me when my email address isn't in
> the headers at all? I even get a news letter that has no headers the
> only way I know what it is is based on their content. I thought that
> routing info was supposed to be included in the headers.

That's what Bcc: is all about, "Blind carbon copy". You'll never see that
header in any received mail, so your rule to look for your address there is
useless. Usually a secondary header such as "Delivered-To:" is added by the
receiving MTA (Mail Transport Agent). You should carefully examine the
headers on such an email to see what header your ISP's MTA adds, and have
your rule examine that header as well.

Your rules as they currently exist are probably removing some valid email.

> I also understand that on a domain certain users are mandatory per
> RFC: abuse, postmaster, <> and a couple of others.
>
> I'm curious as to what <> is as I've seen it in some of the headers I
> logged that I'd tossed. And am I correct in assuming that they never
> should have been routed to me to start with and can safely be routed
> to /dev/null.

"<>" is an address indicating a DSN (Delivery Status Notification) or error
condition from an MTA, and is mandated by RFC 2554. Unfortunately, it is
often used by spammers as a forged address, and so is subject to abuse.


tony

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On Sun, 21 Sep 2003 13:35:56 -0700, ynotssor <> wrote:
> "Michael C." <(E-Mail Removed)> wrote in message
> news:bkkvep$2t3q1$(E-Mail Removed)
>
> > While the junk seems to be slowing down, I've modified spamkill to
> > kill messages that don't have my email in To:, Cc:, or Bcc: before
> > bringing them down from my ISP.
> >
> > How does my ISP route messages to me when my email address isn't in
> > the headers at all? I even get a news letter that has no headers the
> > only way I know what it is is based on their content. I thought that
> > routing info was supposed to be included in the headers.
>
> That's what Bcc: is all about, "Blind carbon copy". You'll never see that
> header in any received mail, so your rule to look for your address there is
> useless. Usually a secondary header such as "Delivered-To:" is added by the
> receiving MTA (Mail Transport Agent). You should carefully examine the
> headers on such an email to see what header your ISP's MTA adds, and have
> your rule examine that header as well.
>
> Your rules as they currently exist are probably removing some valid email.
>

Should the following snippet be relatively benign?

if ($content_type) {
$is_spam = 1 if ($content_type =~ /multipart/ ||
$content_tpe =~ /html/);
$is_spam = 0 if ($to =~ /mcsuper5\@usol\.com/ ||
$cc =~ /mcsuper5\@usol\.com/);
}

I believe this says that if the message is multipart or html it's
spam.
If it is addressed to me personally, it might just be one of my friends
that don't know any better, so keep testing.

I haven't dug up the Perl docs, so I'm sure there is a way to clean it
up, I'd just like to know if I'm misinterpreting what I've got. I'd
asume legitimate administration issues should be plain/text I hope.

Michael C.
--
(E-Mail Removed) http://mcsuper5.freeshell.org/
Registered Linux User #303915 http://counter.li.org/