[Mailman-Users] Help for a new install on Linux

[mailman at tux.org]

On Mon, 30 Sep 2002, Mark Tilden wrote:

> 2. I created a second test list with no spaces in the name. It
> works better.  However, whenever I send mail to the list server, I
> get a "loop back" bounce message from sendmail. Here's the message:
>
> > This is the Postfix program at host gateway.tildens.org.
> >
> > <markstestlist at gateway.tildens.org>: mail for gateway.tildens.org
> > loops back to myself

That's a DNS issue.  Most often when the "loops back to myself" error
shows up, the MX host for the target domain resolves to 127.0.0.1
which clearly creates a loop.  Sometimes, a correctly configured MX
record will still create this problem if the MTA has not been configured
to recognize local mail as such and deliver it differently than other
mail it is relaying.  i.e., if a given MTA has been configured to relay
-everything- based solely on MX records and it discovers that the relay
for a given domain is -itself- (even if the MX record does not point to
"127.0.0.1") it might issue the "loops back to myself" NDR in that case,
too.  (Typically, an MTA for a given domain is configured to either
deliver mail for that domain locally (i.e., to a mailbox) or to use a
specific host as the next-hop relay for that domain (i.e., don't look it
up in DNS).)

While troubleshooting, remember that the view of DNS from the system
in question may be very different from the view of DNS from some other
system, even a "neighbor".

Take a careful look at things; you claim that bounce message comes
from sendmail, but the NDR you provided is from a Postfix MTA.  Did
you mean "the MTA" instead of "sendmail"?  If not, the environment in
which you are operating may be quite different from what you believe
it to be.

HTH
- Andrew

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