On Sat, Dec 30, 2000 at 05:53:08PM +0100,
Peczoli Zoltan <pocok@???> is thought to have said:
> Hello all,
>
> My question is why does Exim accept a simple <> in the 'From' part of the
> SMTP conversation?
>
> It goes like this:
>
> 220 myserver.com ESMTP Exim 3.16 #1 Sat, 30 Dec 2000 17:48:53 +0100
> HELO myclient.com
> 250 myserver.com Hello myclient.com [1.2.3.4]
> MAIL FROM: <>
> 250 <> is syntactically correct
>
> Is this the desired behavior?
>
> When receiving such mail, the From line appears as "Remote Mail Delivery
> System <>"
>
> How can I reject messages with <> in MAIL FROM part?
>
> Thanx:
> Pocok
Yes it is the desired behavior. You do not want to reject these messages.
MAIL FROM:<>
This is a standard SMTP usage to indicate an error message that should not
itself generate another error message. Here are two extracts from RFC1123:
5.2.9 Command Syntax: RFC-821 Section 4.1.2
The syntax shown in RFC-821 for the MAIL FROM: command omits
the case of an empty path: "MAIL FROM: <>" (see RFC-821 Page
15). An empty reverse path MUST be supported.
[...]
5.3.3 Reliable Mail Receipt
When the receiver-SMTP accepts a piece of mail (by sending a
"250 OK" message in response to DATA), it is accepting
responsibility for delivering or relaying the message. It must
take this responsibility seriously, i.e., it MUST NOT lose the
message for frivolous reasons, e.g., because the host later
crashes or because of a predictable resource shortage.
If there is a delivery failure after acceptance of a message,
the receiver-SMTP MUST formulate and mail a notification
message. This notification MUST be sent using a null ("<>")
reverse path in the envelope; see Section 3.6 of RFC-821. The
recipient of this notification SHOULD be the address from the
envelope return path (or the Return-Path: line). However, if
this address is null ("<>"), the receiver-SMTP MUST NOT send a
notification. If the address is an explicit source route, it
SHOULD be stripped down to its final hop.
Tabor
--
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Tabor J. Wells twells@???
Fsck It! Just another victim of the ambient morality
