Re: VGER's filters..

[Matti Aarnio <matti.aarnio@zmailer.org>]

On Fri, Apr 04, 2003 at 12:36:20PM -0800, H. Peter Anvin wrote:
> By author:    Matti Aarnio <matti.aarnio@zmailer.org>
> > <<-  MAIL FROM: <yahoo-dev-null@yahoo-inc.com>
> > ->>  501 5.1.7 strangeness between ':' and '<': <yahoo-dev-null@yahoo-inc.com>
...
> Sendmail, and a whole bunch of other mailers, have taken the more
> liberal approach of allowing any RFC 822-compliant address in this
> place (which is a *lot* more liberal than an RFC 821-compliant
> reverse-path.)  This is consistent with the "be liberal in what you
> accept, conservative in what you send" philosophy of network
> interoperability.

Definitely.  VGER is running fairly liberal mode, while some
other systems I run in extremely strict mode.   As a result,
vger lets in spams, which could be blocked by running strict.

> I suspect in Sendmail it naturally falls out of using a single set
> of canonicalization rules for all syntax.

Nope, the protocol line parser in original version was simple,
it reused same code for "MAIL FROM:" and "RCPT TO:" as for
"From:" and "To:", therefore with old sendmails you could
do in SMTP:
   MAIL FROM: < foo@bar >
   MAIL FROM:   foo@bar
and I think even:
   MAIL FROM: Example User foo@bar

There really was no SMTP protocol parser, there was just something
resembling it on surface.   (And tons of security problems...)

> 	-hpa

/Matti Aarnio