Re: [Exim] AOL - SPF - and EXIM

On Thu, 17 Jun 2004, Valentin Nechayev wrote:

> You can discard these messages

That would be a serious step to take. Much more serious than overtly
refusing mail, IMHO.

> or put them on bigboard,

Sounds like grounds for legal action against the postmaster. Of
course, IANAL.

> but you can't reject it.

7.7 says

It is a well-established principle that an SMTP server may refuse to
accept mail for any operational or technical reason that makes sense
to the site providing the server. However, cooperation among sites
and installations makes the Internet possible. If sites take
excessive advantage of the right to reject traffic, the ubiquity of
email availability (one of the strengths of the Internet) will be
threatened; considerable care should be taken and balance maintained
if a site decides to be selective about the traffic it will accept
and process.

I don't see anything there which prohibits you from deciding to reject
mail "for any operational or technical reason that makes sense to the
site providing the server". It does no more than to ask for care and
balance in the interests of the wider community.

The argument has been exercised repeatedly here that 4.1.4 says:

An SMTP server MAY verify that the domain name parameter in the EHLO
command actually corresponds to the IP address of the client.
However, the server MUST NOT refuse to accept a message for this
reason if the verification fails:

and some appear to claim that this forces you to accept a mail if the
HELO verification fails, overruling any other clauses that would allow
you to reject it. I don't buy that.

Even if I'm told not to reject mail solely on the basis of the
HELO/EHLO domain failing to verify, I'm sure I can find some other
justifiable reason for rejecting such mail, and I reckon 7.7 confirms
my right to do that, even within the scope of the RFC itself.

> If you will reject them, you should be filtered.

To adapt the wording of the RFC to modern conditions, I might say:

Because sites have taken excessive advantage of the right to transmit
traffic, the ubiquity of email availability (one of the strengths of
the Internet) *is* threatened;

We can't unilaterally change that deplorable state of affairs. We can
only do our best to protect our users from the 'net (as well as to
take responsible steps to protect tne 'net from our users, by the
way).