Re: [exim] Is there and logical reason to reject mail from: …

Góra strony
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Autor: Tor Slettnes
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Dla: Exim User's Mailing List
CC: David Brodbeck
Temat: Re: [exim] Is there and logical reason to reject mail from: <> ?

On Oct 13, 2004, at 09:31, Greg A. Woods wrote:
> [ On Wednesday, October 13, 2004 at 10:58:58 (-0400), David Brodbeck
> wrote: ]
>> Personally, on some of my domains I reject mail from <> to several
>> addresses
>> that never send mail, including postmaster. Postmaster is just an
>> alias to
>> another account, so I never send mail with postmaster as the return
>> address.
>> Why should I accept bounces to it?
>
> Well in the case of <postmaster> the whole goal of the address is to
> facilitate remote support and debugging and it's one hell of a lot
> easier to type "<>" when manually testing SMTP connections than it is
> to
> type something long but legitimate in there.


Presumably, the 550 response message would indicate the reason for the
rejection: "This address is never used in outgoing mail; you are
responding to a forged address".


> Also, keep in mind that there's no reason why the envelope sender
> address can't be set to <postmaster@???>. You don't have to
> send messages from a "postmaster" account just to have that happen.


Right - though this does not pertain to this particular discussion.
The question is whether it is OK to reject mail with "MAIL FROM:<>" /
"RCPT TO:<postmaster@???>".

I do the same thing. And I have exhibited some "bad" influence upon
others too, via:


http://tldp.org/HOWTO/Spam-Filtering-for-MX/collateral.html#dsnrealuser

I have come to realize (since this HOWTO was released) that this may
violate RFC2821 and other pertintent docs (including the best-practices
RFC2505) - but it is a bit of a grey area/subject to a bit of
interpretation. If indeed it does, these docs are broken, IMO.

(Certainly, I believe that the listing policy of "dsn.rfc-ignorant.org"
is broken w.r.t. interpretation; I'll contact them about that).


> Don't confuse the problems of sender address forgery with the issues of
> supporting a decent and proper <postmaster> mailbox. I.e. don't cut of
> your nose just to spite your face.


That is also not at issue. Mail to <postmaster> would be accepted,
unless it is a DSN. Since postmaster (or other system users such as
"root", "uucp", etc.) never send mail, they also should not receive
DSNs.

-tor