Autor: Ian Eiloart Data: A: Daniel Tiefnig, exim-users Assumpte: Re: [exim] Refusing MAIL FROM:<> ...
--On 7 August 2006 16:16:37 +0200 Daniel Tiefnig <exim@???> wrote:
> Ian Eiloart wrote:
>>> Yes, but RFC2821 didn't copy the "MUST support" thing. (What can we
>>> learn from this?)
>>
>> Well, if you aren't going to support the syntax, then there's not
>> much point playing the game.
>
> There's still a difference between supporting the syntax and saying "no
> bounce mails here". The latter *might* be ok for systems that don't send
> mail, and therefor should never get any bounces.
You mean mail domains that never send email. So, the requirement here is
that the host be an MX server only for domains that don't send email.
That's OK, then nobody is ever going to do a sender verification callout to
those hosts (except in response to spam). In that case, we'd expect a
sender verification callout to fail. No problem here.
> Allthough I think
> refusing the empty sender is just plain stupid in most (if not all)
> cases, I'm not that sure RFCs really require a 250 response to "MAIL
> FROM:<>".
No, they only require that response from an SMTP server! RFC 2821
*requires* the use of a null sender for several types of message. If you
don't accept "MAIL FROM: <>", then you'll never find out who the intended
recipient is. So, you can't know that the recipient doesn't send email.
Unless the above applies.
> lg,
> daniel
