david rearranged electrons thusly:
> I had configured sendmail for linux system. It working fine when I send a
> mail to registerd domains it works fine but unregister domain it say
> unresolvable host and try to send back a mail to the sender but it gives
> error there.
OK ...
> Mar 12 14:22:59 jewelsindia sendmail[10422]: f2C8qvC10420: to=<[EMAIL PROTECTED]>,
> delay=00:00:01, xdelay=00:00:00, mailer=esmtp, pri=31133, relay=gh23.com,
> dsn=5.1.2, stat=Host unknown (Name server: gh23.com: host not found)
gh23.com apparently doesn't exist.
$ dig gh23.com MX
; <<>> DiG 8.3 <<>> gh23.com MX
;; AUTHORITY SECTION:
com. 2h59m50s IN SOA A.GTLD-SERVERS.NET. hostmaster.nsiregistry.NET. (
[snip]
So you obviously can't send it mail.
> Mar 12 14:23:06 jewelsindia sendmail[10422]: f2C8qxC10422:
> to=<[EMAIL PROTECTED]>, delay=00:00:07, xdelay=00:00:07, mailer=esmtp,
> pri=31233, relay=mail.9netave.com. [216.156.2.60], dsn=4.0.0, stat=Deferred:
> 451 <>... unresolvable host name[202.71.150.104],check your setup.
This is a different story altogether. You have no rDNS configured on your
machine (and your ISP hasn't delegated any ip block to you and/or supplied an
rDNS for your IP). So, 9netave (which hosts jewelsindia.com) is blocking your
mail.
An increasing number of server admins around the world are blocking mail from
IPs with no valid rDNS as 99% of it is spam.
The only way out for you is to configure PTR records, make yourself
authoritative etc for all your MX servers (at least) so that this does not
recur.
ISPs rejecting mail from IPs with no rDNS are making the point that any well
configured mailserver / ISP IP block MUST have valid reverse DNS. There's also
RFC 1123 (Requirement for Internet Hosts) which strongly recommends that rDNS
must be implemented across your whole network.
Several ISPs (Pacific Bell) and email providers (Geocities.Com - which is part
of yahoo) have already adopted this strategy of blocking mail from IPs with no
reverse DNS, as 90% of it is likely to be spam.
You (or rather your ISP, if you have something smaller than a /24 block) have
to fill up this form with APNIC - http://www.apnic.net/db/domain.html - for
registering your reverse DNS allocations with APNIC. But first, set it up on
your DNS servers and load the zonefiles properly.
A detailed note on creating reverse DNS is available at
http://www.apnic.net/db/revdel.html
-s
--
Suresh Ramasubramanian <--> mallet <at> efn <dot> org
EMail Sturmbannfuhrer, Lower Middle Class Unix Sysadmin
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