Delivered to internal network by a host with no rDNS

Solution 1:

1) Sign up for the FBL at yahoo. https://help.yahoo.com/kb/postmaster/

2) Are you respecting NDR and Unsubscription links?

3) Do you have and maintain postmaster@ and abuse@ mailboxes?

It looks like your have good FCrDNS, SPF, DKIM, so it could be user complaints, which you will not know about unless you sign up for FBL.

You are missing an SPF for your mail host

 mail.nationaldebtrelief.com IN TXT "v=spf1 a -all"

You could also run [email protected] and post the link.

Solution 2:

The OP asks (among other things) about this issue:

-1.3 RDNS_NONE Delivered to internal network by a host with no rDNS

This is caused by reverse lookups of 127.0.0.1 returning localhost, commonly caused by redirecting mail in-and-out-of localhost for spam/virus filtering (like through amavis). It will create headers like this with rDNS showing incorrectly for as localhost for 127.0.0.1:

Received: from smtp.example.com (**localhost** [127.0.0.1])
    by smtp.example.com (Postfix) with ESMTPA id A5F13FEF
    for <[email protected]>; Wed, 26 May 2021 17:07:02 -0700 (PDT)

Note that I added *'s around **localhost** above to highlight the issue. By updating /etc/hosts file and placing your hostname before the word localhost it will be be placed correctly in your logs:

So you want this:

~]$ cat /etc/hosts
127.0.0.1   smtp.example.com localhost localhost.localdomain 
::1         smtp.example.com localhost localhost.localdomain

not this:

~]$ cat /etc/hosts
127.0.0.1   localhost localhost.localdomain smtp.example.com
::1         localhost localhost.localdomain smtp.example.com

and definitely not this:

~]$ cat /etc/hosts
127.0.0.1   localhost localhost.localdomain
::1         localhost localhost.localdomain

... or you can configure rDNS for 127.0.0.1 but that seems silly...just what hostname should a centralized rDNS server respond with? Indeed, it can't ;)