On Nov 9, 2011, at 5:57 PM, 风河 wrote: > I have two server IPs, the A records for them are: > > mail.dnsbed.com. 300 IN A 74.117.233.4 > mail.dnsbed.com. 300 IN A 74.117.232.204 > > The corresponding PTR records are: > > 4.233.117.74.in-addr.arpa. 36466 IN PTR dnsbed.com. > 204.232.117.74.in-addr.arpa. 36453 IN PTR dnsbed.com.
So a double-reverse lookup check will fail, because the PTR records go to dnsbed.com and not to mail.dnsbed.com. > But this setting can't make email sending successful. > The Postfix system says: > > postfix/smtp[13775]: A65713180D9: to=<***@freenet.de>, > relay=mx.freenet.de[195.4.92.211]:25, delay=1.2, > delays=0.29/0.02/0.76/0.16, dsn=5.0.0, status=bounced (host > mx.freenet.de[195.4.92.211] said: 550 inconsistent or no DNS PTR > record for 74.117.233.4 (see RFC 1912 2.1) (in reply to RCPT TO > command)) > > > Is there any RFC item said the A and PTR records must be consistent? > And why they must? Why, yes-- by "see RFC 1912 2.1", they mean: http://www.ietf.org/rfc/rfc1912.txt This is only a "should" recommendation, and not a "must" requirement. freenet.de appears to be enforcing a rather strict policy check here, but a DNS mismatch is a decent indicator of spammy mailservers; I'd use it for scoring purposes myself, and not as an absolute pass/fail. Regards, -- -Chuck _______________________________________________ Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
