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I have installed centos7, whm/cpanel and mailwizz on amazon ec2 instance, managing DNS through cloudflare.com. Everything is fine i have issue with rDNS even i have created PTR records in Route53 and WHM. WHM still shows following issue with PTR in Email Deliverability section.

The system sends “app.mydomain.com”’s outgoing email from the “1.2.3.4” IP address. The only PTR value for this IP address must be “app.mydomain.com”. This is the name that this server sends with SMTP’s “HELO” command to send “app.mydomain.com”’s outgoing email.

1 unexpected PTR value exists for this IP address:

ec2-1-2-3-4.eu-west-2.compute.amazonaws.com

To fix this problem, replace all PTR records for “4.3.2.1.in-addr.arpa” with the following record at “pdns1.ultradns.net”, “x1.amazonaws.com”, “x2.amazonaws.com”, “x3.amazonaws.org”, and “x4.amazonaws.org”: Suggested “PTR” (PTR) Record PTR
Name: 4.3.2.1.in-addr.arpa.
Value: app.mydomain.com.

When i run this command nc -vv localhost 25
Result: localhost [127.0.0.1] 25 (smtp) open 220-app.mydomain.com ESMTP Exim 4.91 #1 Sat, 13 Apr 2019 15:48:17 +0000 220-We do not authorize the use of this system to transport unsolicited, 220 and/or bulk e-mail.
any solution?

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If that 1.2.3.4 is AWS address you have no control over the PTR records. You have to ask AWS to create the PTR record in their DNS. I have done that in the past and I believe there is a form for it somewhere.


Background: Obviously AWS has control over the reverse DNS of their IPs. Even if you created 3.2.1.in-addr.arpa. zone in UltraDNS it won’t work because this zone of yours is not linked through NS records to the parent zone (e.g. to 2.1.in-addr.arpa.).

On the other hand it’s not 100% necessary to match the HELO hostname with what the reverse DNS hostname, your email will still work, especially if you set up SPF records correctly.

Alternatively send the outbound emails through AWS SES - Simple Email Service - that’s a service that’s properly configured and can deliver the emails for you with a very high success rate.

Hope that helps :)

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