Re: fckng null sender with Exim

[Bulent Murtezaoglu <bm@acm.org>]

>>>>> "ELBnet" == Tech Support <support@elbnet.com> writes:

    ELBnet> Try using: headers_check_syntax = true headers_checks_fail
    ELBnet> = true
    ELBnet> which checks to be sure the From To BCC etc. are correctly
    ELBnet> formatted and rejects them if not.

Which would do you no good for two reasons:

1- The original poster wants to block the null sender in the envelope
from.

2- The null sender is a legitimate envelope from.

Based on my e-mail interaction with the original poster (sender ?) 
I think what is being missed here is RFC 1123 which says 

           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.
      
and again in summary table 5.4, it says RECEIVER-SMTP  _MUST_ send
error notification messages using the null return path.

If you block the null sender some nasty things happen.  For example
your customer sends off an important price quote to an important
customer using the wrong e-mail address, the mail gets queued
in some relay and eventually gets bounced (with null envelope sender),
but since you refuse such messages your customer never finds out.

I occasionally go through host requirements RFC's because admins
elsewhere break things.  This particular bit of chapter and verse 
from 1123 comes to you courtesy of an interland client...

cheers,

BM