D G Teed wrote:
On Thu, Nov 13, 2008 at 2:14 PM, mouss <[EMAIL PROTECTED]> wrote:
We send non-delivery responses.
if these are "user does not exist" or "filter thinks this is spam/virus"
and the like, then you are a backscatter source.
I don't think we "send" NDRs as emails originating here.
I think we reject emails. Maybe you can tell me.
I test emailed a bogus address at work from home. My home ISP's
SMTP server sent back a NDR, not my work's MX server.
Inside the NDR from my home ISP's SMTP,
I see reference to the name of one of the workplace MX servers,
but the Reporting-MTA is that of the home ISP, not work's MX.
That's still backscatter even if it is your ISP that generates it. if
you ISP can't get the list of valid email addresses, it is better not to
use it as an MX (and use your server instead). some providers now
discard such mail (do not generate NDRs) because of backscatter. not
ideal, but backscatter is a real problem (you know that when you get hit
by a backscatter storm).
PS. In this case, it is the ISP server that may be listed, not yours.
In this thread I've posted my postconf -n output.
We user virtual_alias_maps and
smtpd_client_restrictions = reject_unlisted_recipient
is at the beginning of our list of restrictions.
This causes email to be rejected for non-delivery. We do not
relay to our Exchange or Cyrus server only to find out
at that stage the email address does not exist. Our mapping
file (virtual_alias_maps) is the complete list of all addresses and
what final server they go to.
[EMAIL PROTECTED] [EMAIL PROTECTED]
Does this not achieve the same result as using relay_recipient_maps ?
it's ok on your server. but the problem is on your ISP server. it is
relaying mail without knowing the list of your valid recipients.
