mail# dig dprc.ru mx

; <<>> DiG 8.3 <<>> dprc.ru mx
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 3, ADDITIONAL: 1
;; QUERY SECTION:
;;      dprc.ru, type = MX, class = IN

;; ANSWER SECTION:
dprc.ru.                15M IN MX       10 ics.dprc.ru.

;; AUTHORITY SECTION:
dprc.ru.                15M IN NS       ns.masterhost.ru.
dprc.ru.                15M IN NS       ns1.masterhost.ru.
dprc.ru.                15M IN NS       ns2.masterhost.ru.

;; ADDITIONAL SECTION:
ics.dprc.ru.            15M IN A        85.21.210.174

;; Total query time: 116 msec
;; FROM: mail.strs.ru to SERVER: default -- 213.221.1.167
;; WHEN: Thu May 21 11:46:01 2009
;; MSG SIZE  sent: 25  rcvd: 125

mail#
mail# dig isc.dprc.ru a

; <<>> DiG 8.3 <<>> isc.dprc.ru a
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 4
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0
;; QUERY SECTION:
;;      isc.dprc.ru, type = A, class = IN

;; AUTHORITY SECTION:
dprc.ru.                14m16s IN SOA   ns1.masterhost.ru. hostmaster.masterhost.ru. (
                                        1200651122      ; serial
                                        8H              ; refresh
                                        2H              ; retry
                                        2W              ; expiry
                                        10M )           ; minimum

;; Total query time: 6 msec
;; FROM: mail.strs.ru to SERVER: default -- 213.221.1.167
;; WHEN: Thu May 21 11:46:34 2009
;; MSG SIZE  sent: 29  rcvd: 91

mail#

mail# nslookup isc.dprc.ru
Server:  ns.s.ru
Address:  2.2.1.1

*** ns.strs.ru can't find isc.dprc.ru: Non-existent host/domain

для сравнения

mail# dig mail.co.ru a

; <<>> DiG 8.3 <<>> mail.co.ru a
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 3, ADDITIONAL: 3
;; QUERY SECTION:
;;      mail.co.ru, type = A, class = IN

;; ANSWER SECTION:
mail.co.ru.             10M IN A        194.186.47.75
mail.co.ru.             10M IN A        194.186.47.76
mail.co.ru.             10M IN A        194.186.47.77

;; AUTHORITY SECTION:
co.ru.                  12H IN NS       ns1.gldn.net.
co.ru.                  12H IN NS       ns2.gldn.net.
co.ru.                  12H IN NS       ns3.gldn.net.

;; ADDITIONAL SECTION:
ns1.gldn.net.           1d15h20m IN A   194.67.2.108
ns2.gldn.net.           1d15h20m IN A   194.67.2.109
ns3.gldn.net.           1d15h20m IN A   194.67.7.1

;; Total query time: 32 msec
;; FROM: mail.strs.ru to SERVER: default -- 213.221.1.167
;; WHEN: Thu May 21 11:47:15 2009
;; MSG SIZE  sent: 28  rcvd: 186

mail#

в результате

May 20 14:32:32 mail sendmail[92710]: n4KAWRA5092710: syslog:check_mail:<a.Lukyantseva@dprc.ru>
May 20 14:32:32 mail sendmail[92710]: n4KAWRA5092710: ruleset=check_rcpt, arg1=<pergo@strs.ru>, relay=isc.dprc.ru [85.21.210.174] (may be forged), reject=550 5.7.1 <pergo@strs.ru>... Denied (dns rule 2). IP name forged \0021
May 20 14:32:32 mail sendmail[92710]: n4KAWRA5092710: from=<a.Lukyantseva@dprc.ru>, size=7393, class=0, nrcpts=0, proto=ESMTP, daemon=MTA, relay=isc.dprc.ru [85.21.210.174] (may be forged)
mail#

R$*             $: < $&{client_resolve} >
R<FORGED>       $#error $@ 5.7.1 $: "550 Denied (dns rule 2). IP name forged $&{client_name}

чья проблема? отправляющей или принимающей стороны?