> I am subscribed to several mailing-lists and they never send me these
> error-messages, so my question is: how do you do that?
First of all: Errors-To should never be used in outgoing mail, and
it should never be honored by any MTA. Errors-To is not a standard
header. MTAs should *always* send error messages to the envelope
return address, which appears in the MAIL FROM command of the SMTP
envelope, or if not in SMTP, in the Return-Path header.
Every MTA that I know of that supports Errors-to also does things
the right way if Errors-To is not present, so it's arguably better
to leave Errors-to out of the message. What's more, the presence of
multiple possible error reporting addresses makes for ambiguous handling
at best (where does the message go if there is a choice?). (and no,
setting them all to point to the same place doesn't always work
because there's a possibility that list down stream will rewrite
one of them and not the other.)
Second: if you run a list, the way you get bounces to go to the list
maintainer is to set the envelope return path (SMTP MAIL FROM) to
point to the address of the list maintainer. This isn't done by
adding a message header. If the list sends mail using sendmail,
the -f command-line option can be used to set the envelope return path.
Third: many mailers and gateways are broken in that they return mail
to the header From address instead of the envelope return address.
Some lists set the From address on outgoing mail to point to the
list (a very ugly thing to do IMHO), and try to filter error messages
to keep them from being sent back to the list. I've seen
disasterous results from this approach, either because the list filtered
out perfectly valid messages, or because the list let some slip through.
Some lists do this better than others, but fortunately, most lists just
set the envelope return address to the right place and leave
the From header alone.
What this generally means is that the list maintainer gets bounces
from mailers that work, and the submitter of a message gets bounces
from broken mailers. (but at least they don't go to the whole list)