From: Victor Duchovni (no email)
Date: Mon Apr 16 2007 - 10:51:42 EDT
On Mon, Apr 16, 2007 at 04:38:23PM +0200, mouss wrote:
> so, I've never seen it block spam, but it has been reported to block
> legitmate mail. and from a standard perspective, nothing prohibits a
> multi-recipient mail with a null sender.
Three plausible ways in this types of mail can be legitimate:
- Legitimate bulk-mail sending software uses <> instead of DSN
NOTIFY=NEVER to suppress bounces (the DSN approach is not always
effective). In most cases the sending software *should* be handling
bounces to aid with list management.
- Legitimate bulk-lmail sending software uses DSN NOTIFY=NEVER, but
an intermediate DSN capable relay replaces the envelope sender with
<> when forwarding to a non-DSN relay. Again bulk-mail should not
ignore or discourage bounces.
- Actual bounces returning to the responsible party are delivered
to a group mailbox, and forwarded to the members of the group. This
type of mail appears from outside your domain, when some of your
users collectively own/manage an external mailbox.
In most cases any collateral damage from filtering multi-recipient bounces
should be low. Whether there is any benefit to blocking this type of mail
is less clear.
-- Viktor. Disclaimer: off-list followups get on-list replies or get ignored. Please do not ignore the "Reply-To" header. To unsubscribe from the postfix-users list, visit http://www.postfix.org/lists.html or click the link below: <mailto:?body=unsubscribe%20postfix-users> If my response solves your problem, the best way to thank me is to not send an "it worked, thanks" follow-up. If you must respond, please put "It worked, thanks" in the "Subject" so I can delete these quickly.