> On Aug 24, 2017, at 11:49 AM, admin@??? wrote:
>
> https://bugs.exim.org/show_bug.cgi?id=2159
>
> --- Comment #3 from Graeme Vetterlein <graeme.exim4@???> ---
> Andreas,
>
> Yes I believe so. My ISPs relay is rejecting the message in this specific
> situation. If only one user forwards it accepts it . With two (or more?) it
> rejects it in this fashion. I would have expected the two .forwards to operate
> independently .
Mail from the empty sender address is typically expected to be a bounce, and
so directed at just one mailbox. Lists that expand to multiple users should
not in general be the envelope senders of email, so bounces are broadly
expected to not expand to multiple users en-route. Therefore, some receiving
systems enforce single-recipient bounce messages.
FWIW, Postfix even has a feature to implement precisely such a policy:
http://www.postfix.org/postconf.5.html#reject_multi_recipient_bounce
Reject the request when the envelope sender is the null address,
and the message has multiple envelope recipients. This usage has
rare but legitimate applications: under certain conditions,
multi-recipient mail that was posted with the DSN option
NOTIFY=NEVER may be forwarded with the null sender address.
and I expect that though not extremely popular, this is used at a
non-negligible number of sites.
--
Viktor.
