sendmail: sender domain must resolve

[Mathias Körber]

What system is your user using as SMTP server? Is that the server
that reports the error, or does that come somewhat later
as bounce-mail from some other server?

I checked out your domain and it looks ok at first glance, except for =
one thing:

	;; ADDITIONAL SECTION:
	dns1.netlimited.net.    1d12h46s IN A   209.196.128.11
	dns2.netlimited.net.    1d12h46s IN A   209.196.128.12

Both nameservers for your zone are located in the same /24 network.
(a traceroute poves that)

So if there is a network problem, BOTH will be unreachable, and that =
could
result in the problem you observed (and others). You should have =
secondary
nameservers that are located on different networks, powersupplies etc
(see RFC2182 Section 3.1)



> -----Original Message-----
> From: shiva at mail.well.com [mailto:shiva at mail.well.com]On Behalf Of
> Kenneth Porter
> Sent: Saturday, November 04, 2000 10:03
> To: bind-users
> Subject: sendmail: sender domain must resolve
>=20
>=20
>=20
> One of my users using Eudora is experiencing 451 "sender domain must
> resolve" errors intermittently when attempting to send mail. (I've
> confirmed this by checking my sendmail log, and it's not limited to a
> single user.) He is using @kensingtonlabs.com as his envelope domain. =
I
> checked with nslookup and it looks like our domain provider
> (dns1.netlimited.net) is reporting the correct MX record for this
> (priority 20, smtp.kensingtonlabs.com). Meanwhile, ns.brainstorm.net =
is
> providing a valid PTR record for our mail server. At some point the
> mail finally does go through.
>=20
> This looks like an intermittent DNS problem, but I don't see anything
> in my logs. Do I need to add some log-enabling lines to my
> bind-8.2.2-P3 setup? (I don't currently have anything about logging in
> named.conf.) The only named messages I see in /var/log/messages are a
> periodic statistics message and occasional lame server reports.
>=20
> The mail server is also the gateway and a caching DNS for our internal
> LAN. It only listens to the LAN and forwards to Brainstorm.
>=20
> Ken
> mailto:shiva at well.com
> http://www.sewingwitch.com/ken/
> http://www.harrybrowne2000.org/
>=20
>=20
>=20
>=20