Bill Moseley wrote:
> Att.net is reporting a DNS lookup failure on a domain I run. I don't
> see any problems but just curious if anyone is familiar with issues
> with att.net or might have an idea what might be the problem.
>
> A sanity check, if you will.
>
>
> I host a domain whmoseley.com. One sender can only get mail through
> about 1 in 5 tries. Most of the time she gets a bounce:
>
> From: postmaster@??? (Webmail Postmaster)
> To: ******@att.net
> Subject: Returned mail: User unknown
> Date: Thu, 25 Jan 2007 20:31:17 +0000
>
> The following addresses had fatal errors:
> *****@whmoseley.com: 550 [PERMFAIL] destination not valid within DNS
>
> Which is not the most helpful message -- "User unknown" in the subject
> but the DNS error in the body. And no other info, like what server
> had the DNS lookup error.
>
>
> That message never got to my Exim4 machine. The domain gets fifty or
> so other emails a day without any problems. But this one user
> consistently has problems.
>
> The only thing odd about that domain is that there's no A DNS record
> only an MX -- which shouldn't be a problem.
>
> The dns boxes are on the same sub-net, which is not great, but doesn't
> explain why it's only that one sender with problems.
>
> $ dig mx whmoseley.com. | grep mail
> whmoseley.com. 86400 IN MX 5 mail.whmoseley.com.
>
> $ dig a mail.whmoseley.com. | grep 170
> mail.whmoseley.com. 86368 IN A 63.205.225.170
>
> Or:
>
> $ host whmoseley.com
> whmoseley.com mail is handled by 5 mail.whmoseley.com.
>
> $ host mail.whmoseley.com
> mail.whmoseley.com has address 63.205.225.170
>
> Any ideas?
>
>
>
>
Their message may not say so specifically, but I would suspect rDNS and/or
forward/reverse lookup mismatch:
triligon# dig ptr whmoseley.com
; <<>> DiG 9.3.2-P1 <<>> ptr whmoseley.com
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 49648
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0
;; QUESTION SECTION:
;whmoseley.com. IN PTR
;; AUTHORITY SECTION:
whmoseley.com. 10800 IN SOA ns1.hank.org.
hostmaster.whmoseley.com. 2004022241 86400 3600 604800 86400
And then:
triligon# host 63.205.225.170
170.225.205.63.in-addr.arpa is an alias for 170.168.225.205.63.in-addr.arpa.
170.168.225.205.63.in-addr.arpa domain name pointer mardy.hank.org.
Besides the IP aliasing, mardy.hank.org and mail.whmosely.com do not match, even
if their lookup proceeds that far...
HTH,
Bill
