[Exim] RFCs and Null senders <>

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Author: Xander D Harkness
Date:  
To: exim Users
Subject: [Exim] RFCs and Null senders <>
I have a query regarding the null sender that is frequently used for
bounces and warnings.

I have read through RFC2822 and specifically the following:

Here are the bits:

sender          =       "Sender:" mailbox CRLF
mailbox         =       name-addr / addr-spec
name-addr       =       [display-name] angle-addr
angle-addr      =       [CFWS] "<" addr-spec ">" [CFWS] / obs-angle-addr
addr-spec       =       local-part "@" domain


So it can't be less than Sender: <@> even if the local-part and domain can be
null. I don't know about the obsolete definition.

If I read RFC2821 it states that for undeliverable mail the return path should be set to <>

This notification message must be from the SMTP server at the relay
host or the host that first determines that delivery cannot be
accomplished. Of course, SMTP servers MUST NOT send notification
messages about problems transporting notification messages. One way
to prevent loops in error reporting is to specify a null reverse-path
in the MAIL command of a notification message. When such a message
is transmitted the reverse-path MUST be set to null (see section
4.5.5 for additional discussion). A MAIL command with a null
reverse-path appears as follows:

      MAIL FROM:<>


As discussed in section 2.4.1, a relay SMTP has no need to inspect or
act upon the headers or body of the message data and MUST NOT do so
except to add its own "Received:" header (section 4.4) and,
optionally, to attempt to detect looping in the mail system (see
section 6.2).

Are these two at odds? - Or am I mis-reading the RFCs

On a separate topic...

I thought I would also mention - for those installing exim at small sites I have put together a small web GUI sort of thing. I know that GUIs for exim have occasionally been shunned on this list; however a small interface to adding new aliases or creating new users and passwords for smtp auth does not need much knowledge. I have found it useful for many contracts where someone who only has knowledge of pointy clicky things is left to perform routine duties.

http://www.harkness.co.uk/exim/exim_gui.html

There is a demo to play with here: http://www.harkness.co.uk/exim/web_gui/

Kind regards
Xander