Re: [Exim] Null Sender

>From: Gururajan Ramachandran <grr@???>
>To: exim-users@???
>Subject: [Exim] Null Sender
>Date: Fri, 11 Jul 2003 07:04:33 -0400
>
>I know that Null Sender is valid as per RFC.
>
>However, is there a way to block email at the SMTP level that have
>both Null Sender *AND* attachments?

Not quite sure why you'd want to do this.

You should be able to do this with exim-4.20 + Tom Kistner's
exiscan-acl-4.20-09.patch. In the macros section at the head of the
main section put something like:


# A list of file extensions that may be harmful to the health &
# welfare of crippleware on Windows machines.
NASTIES1 = ade:adp:bas:bat:chm:cmd:com:cpl:crt:eml:exe:hlp
NASTIES2 = hta:inf:ins:jse:lnk:mdb:mde:msc:msi:msp:mst:pcd
NASTIES3 = pif:reg:scr:sct:shs:url:vbs:vbe:wsf:wsh:wsc
NASTYGRAMS = NASTIES1:NASTIES2:NASTIES3


Then, as part of your acl_smtp_data ACL, have somthing like:

  # Reject messages that have serious MIME errors.  This calls the
  # demime condition.  Note that the results of demime are cached, so
  # we can freely use it later in this ACL.
  deny  message = Serious MIME defect detected ($demime_reason)
        demime = *
        condition = ${if > {$demime_errorlevel}{2} {yes}{no}

  # The following should reject email from null senders with
  # unwanted attachments.
  deny  message = bounce message with blacklisted file attachment ($found_extension)
        senders = :
        demime = NASTYGRAMS

Note I haven't tried the above. Use at your own risk!