Double Irony! (was Re: [linux-elitists] ruben's stupid filter)

Rick Moen
Mon Mar 25 08:08:57 PST 2002

Quoting Dan Wilder (

> Ah, dang.  I knew you'd ask me that.  Lemmeesee ... mumble mumble ...
> ahh, here it is.  RFC1123.
>       5.2.5  HELO Command: RFC-821 Section 3.5
>          The sender-SMTP MUST ensure that the <domain> parameter in a
>          HELO command is a valid principal host domain name for the
>          client host.  As a result, the receiver-SMTP will not have to
>          perform MX resolution on this name in order to validate the
>          HELO parameter.
>          The HELO receiver MAY verify that the HELO parameter really
>          corresponds to the IP address of the sender.  However, the
>          receiver MUST NOT refuse to accept a message, even if the
>          sender's HELO command fails verification.
> No doubt there's good reason.   It likes me not.  That guy MUST do
> this, but you MUST NOT insist on it.   A standard without a
> consequence.

The "good reason" may have been merely that some large site du jour
was expected to dig in heels and say "No, we don't intend to fix our
broken HELO support any time soon.  Have a nice day."  The rationale
may have been nothing more lasting than that.

Cheers,      "Transported to a surreal landscape, a young girl kills the first
Rick Moen     woman she meets, and then teams up with three complete strangers       to kill again."  -- Rick Polito's That TV Guy column,
              describing the movie _The Wizard of Oz_

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