about the A and PTR for sending mail

[Mark Andrews]

In message <CAA3U4eMEHMG0Nx9ry==zYBGJTMnbb4_y+npHzwKCzKehsWTT2A at mail.gmail.com>,
 =?UTF-8?B?6aOO5rKz?= writes:
> Hi,
> 
> I know maybe this is not related to DNS question, so please excuse me
> if it's not that suitable.
> 
> 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.
>
> 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?

While there is no RFC requirement that they match is there any
reason not to make them match (the above records don't match)
given that is the intent of the IN-ADDR.ARPA namespace?

> Thanks.
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-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org