🚀 go-pugleaf

les@chinet.chi.il.us (Leslie Mikesell) writes about twiddling
     with headers before sending mail to a mailing list:
 > There are some problems any way you try to handle this, mostly due to
 > lack of compatibility among mailers.  
 > If you simply leave the message alone and forward it to everyone on the
 > list, delivery error messages will go back to the sender who is unlikely
 > to be able to do anything about the bad addresses in the list.

True enough.  I run a couple of mailing lists and I use a
program that adds a Sender header pointing to the -request
address for the lists.  It also uses the sendmail's -f flag to
forge the envelope information for added insurance.

 > If everyone ran sendmail perhaps you could use the Errors-To:
 > header.  They don't.

The Sender header should be sufficient for RFC 822 compliant mail
agents.  Forging the envelope should suffice for the rest.

 > Another recently-posted message shows how to get the
 > "Envelope-From" of the message to point to the list
 > maintainer, so the error messages will go there instead.
 > However, lots of UA's on uucp machines generate replies back
 > to the Envelope-From (the From_ line in uucp mail), since that
 > is often more likely to work than whatever your neighboring
 > site did to the "From: " line.  So you're going to get some
 > replies tossed at the list maintainer.

True enough.  The question is whether the number of misdirected
messages be managable.  I'd rather have a few messages come back
to me, than have even one bounced message fly back into the faces
of a hundred fifty mailing list readers.  Forwarding the
occasional misdriected message to the list isn't difficult.

 > Also, I haven't seen a mailer that allowed replying only to
 > the "To:" address, so the reply will include a copy to the
 > sender who is undoubtedly also on the list.

Not undoubtedly.  Most of the time, if the mailing list isn't
gatewayed to the news system.  Considerably less often than that
if there's a bidirectional link between USENET and the mailing
list.  If you're not the list maintainer, you'll have a tough
time figuring it out whether the author is on the list or not.

 > Some software is smart enough to transport a single copy back
 > to the list exploder which might be able to figure out that
 > there is a duplication and eliminate it.  Only some...

Receiving a duplicate is better than receiving no reply at all!

 > Many UA's on uucp machines will generate replies to the To:
 > and Cc: headers by evaluating the From_ line to generate a
 > path back to the sending machine to be sure the address is
 > evaluated in the same context as when originally sent.  This
 > means that if you do not rewrite the From_ line at the list
 > exploder site, the reply is likely to be routed back through
 > the senders site before going to the list exploder (and
 > replies to the reply will keep growing longer paths).

This reason aside, I recommend rewriting the From_ to keep UUCP sites from sending
boucnes back to the message author, instead of to the list
maintainer.

Old UUCP mailers simply don't have a way of distinguishing the
sender from the author, so I don't think there's any way to help
them, other than installing more capable mailers.  The mailer
doesn't have to conform to the Internet RFCs as long as there is
_some_ way translating between the two and not losing essential
information.  I.e. some way for a gateway between the two nets to
do the right thing.

 > Does anyone have a universal solution?

Well, I don't, but I do have mailing list gateway software that
works well for the lists that I run.  I understand that Rich $alz
also has some code that he's willing to share.