Date: Sun, 7 Sep 1997 19:25:36 -0700 From: John-Mark Gurney <gurney_j@efn.org> To: hackers@hub.freebsd.org Subject: Re: spam and the FreeBSD mailing lists Message-ID: <19970907192536.54931@hydrogen.nike.efn.org> In-Reply-To: <199709080148.SAA25601@hub.freebsd.org>; from Jonathan M. Bresler on Sun, Sep 07, 1997 at 06:48:46PM -0700 References: <19970907181727.43084@hydrogen.nike.efn.org> <199709080148.SAA25601@hub.freebsd.org>
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Jonathan M. Bresler scribbled this message on Sep 7:
> John-Mark Gurney wrote:
> >
> > > please remember to distinguish between "mail from:" addresses
> > > and relays. there is *not* reasone that i know of that a
> > > "mail from:" address must be resolvable.
> > > if the "don't get your ACK's ba" they cant establish the TCP
> > > session in order to transfer the mail in the first place.
> >
> > actually.. yes it does... the mail from: is exactly that... the return
> > path... i.e. if it isn't resolvable, then it's not a valid return path...
> > now if you provide a uucp address.. then it's a bit harder to verify
> > that it's valid...
>
> have we talked about x.400 yet?
> the "mail from" might even be a martian network behind some
> relay.
>
> only the relay has to be contactable via TCP/IP.
> not the "mail from:"
no... your not correct... read what the rfc821 has to say about it:
MAIL <SP> FROM:<reverse-path> <CRLF>
This command tells the SMTP-receiver that a new mail
transaction is starting and to reset all its state tables and
buffers, including any recipients or mail data. It gives the
reverse-path which can be used to report errors. If accepted,
the receiver-SMTP returns a 250 OK reply.
The <reverse-path> can contain more than just a mailbox. The
<reverse-path> is a reverse source routing list of hosts and
source mailbox. The first host in the <reverse-path> should be
the host sending this command.
two key sentences... a) "It gives the reverse-path which can be used to
report errors." b) "The frist host in the <reverse-path> should be the
host sending this command." basicly it states that the MAIL From must
be a perfectly representable mail address to YOU... if this forces the
person to add "@relay.host.name" at the end, then be it.. but it clearly
states that if the recieving end doesn't accept it, they don't have to...
> two more bite the dust:
>
> Sep 7 18:18:31 hub sendmail[23726]: NOQUEUE: ruleset=check_relay, arg1=imsp015.netvigator.com, arg2=205.252.144.206, relay=root@localhost, reject=521 blocked.contact postmaster@FreeBSD.ORG
> Sep 7 18:32:45 hub sendmail[24585]: SAA24585: ruleset=check_mail, arg1=<amish1@cyberamish.com>, relay=root@[205.164.68.2], reject=521 <amish1@cyberamish.com>... specially processed assorted meats? yuck!
I like the last one.. :)
--
John-Mark Gurney Modem/FAX: +1 541 683 6954
Cu Networking
Live in Peace, destroy Micro$oft, support free software, run FreeBSD
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