Re: VGER's filters..

H. Peter Anvin
2003-04-04T20:25:23Z

Followup to: <20030404181054.GT29167@mea-ext.zmailer.org>
By author: Matti Aarnio <matti.aarnio@zmailer.org>
In newsgroup: linux.dev.kernel
>
> With Yahoo I had at first immense problems to get any email from them,
> as their SMTP email sender uses INVALID protocol:
>
> <<- MAIL FROM: <yahoo-dev-null@yahoo-inc.com>
> ->> 501 5.1.7 strangeness between ':' and '<': <yahoo-dev-null@yahoo-inc.com>
> When you read really carefully RFC 821 / 2821 syntax about that,
> you will see that it does not allow space in that place.
> Sendmail does, and that has forced others to extend the syntax alike.
>

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.

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

-hpa
--
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