[plug] Return Receipt on List (was M$ wants you to pay & Mac to go OSS)

John Summerfield summer at os2.ami.com.au
Sun Mar 21 14:53:41 WST 1999


On Sat, 20 Mar 1999, alex polglaze wrote:

> Bret Busby wrote:
> > 
> > -----Original Message-----
> > From: owner-plug at linux.org.au [mailto:owner-plug at linux.org.au]On Behalf
> > Of Christian
> > Bret Busby wrote:
> > > What is the problem with the receipting?
> I have been using Netscape Navigator e-mail for 2 years and have NEVER
> had an e-mail from Brett or anybody else ask me for a receipt.


Since this arose, I've been looking at headers and trying this receipt
stuff myself. Here are my discoveries:
Brett's mailer inserts this:
Disposition-Notification-To: "Bret Busby" <bret at clearsol.iinet.net.au>

I suspect that this is a Microsoft Standard: Sendmail acts on
"Return-Receipt-To:" headers.

Netscape does NOT insert a "Disposition-Notification-To:" header. I tried
using it to request notification.

My procmail filter filtered a bunch of receipts to my bounces folder. These
asserted the mail had been delivered to my mailbox.

As many folks' mailboxes are temporary repositories for mail that will be
collected (perhaps by fetchmail) and further distributed, this receipt
doesn't mean much.

When sendmail sends the receipt, the header requesting it is deleted. This
means that the sender isn't notified of further deliveries. It also means
that mail to mailing lists will NOT be acknowledged by individual
recipients, at least if the sites hosting the list use sendmail to receive
mail.

Additionally, as the receipt is sent by sendmail, users are not aware of
it.

Users may wish to turn off these notifications: as others have noted, the
information can be used by spammers to obtain (with
Disposition-Notification-To:) or verify (with Return-Receipt-To:) email
addresses.

With sendmail, one turns  it off in the m4 configuration files
(your.domain.m4 is a good place: 
   define(`confPRIVACY_FLAGS', `goaway,authwarnings')dnl
if you're not using m4 config files, then review this in your sendmail.cf
O PrivacyOptions=goaway,authwarnings

This disables various address checks otherwise available to remote users.

Note: I'm using sendmail 8.9.x - earlier versions may differ a little.

To disable the Microsoft Standard, you need a procmail filter, maybe like
this:

:0f:
* ^Disposition-Notification-To:
| $HOME/bin/fixmail 

 $HOME/bin/fixmail should contain these eight lines:

#!/usr/bin/perl
while ($L = <STDIN>)
   {
      next if $L =~ /^Disposition-Notification-To:/i;
      print "$L";
      last if $L=~ /^$:/; # stop at blank line twixt headers
   }
print <>;   # print the rest

Don't forget to
   chmod +x $HOME/bin/fixmail

Note: I've not tested the above script. use it at your own risk. It might
do what I say...

If the above recipe is the first procmail works on, all the mail coming in
will have "Disposition-Notification-To:" headers removed.


-- 
Cheers
John Summerfield
http://os2.ami.com.au/os2/ for OS/2 support.
Configuration, networking, combined IBM ftpsites index.



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