Servers' Reverse DNS


Is there a particular reason why at least some of the servers’ reverse DNS do not match their forward DNS names?

*Note: As a nonnative English speaker the use of apostrophe is hard.

The IP addresses of our inbound servers do not send e-mail, therefore they do not require PTR records.

My recommended SPF record is "v=spf1 -all" point to ony 1 IP:
Reverse DNS for that IP does not match

Perhaps I do not understand how MXroute delivers messages.

An SPF include for is an instruction to include an SPF record @ the root domain on, which is not the A record for but is currently this:

“v=spf1 -all”

Following that further you’ll find the SPF behind reveals:

“v=spf1 ip4: ip4: ip4: ip4: ip4: ip4: ip4: ip4: ip4: ip4: ip4: ip4: ip4:” “1/32 ip4: ip4: ip4: ip4: ip4: ip4: ip4: -all”

IPs that send email are found in here, though they may not all be active at a given moment. You’ll notice that has another nested SPF under it that can be used to further locate more IPs that we authorize for our sending infrastructure.

We have a very complex sending infrastructure.

Silly me, I just verified with dmarcanalyzer.
So, the answer for my initial question is: Because it does not matter!
Thank you both!

You can use the mxtoolbox SPF record tool to trace through all the IPs yourself (follow the includes):

starting with

Highly recommend to see how your email looks to recipients. It’ll actually go through our infrastructure and then judge the end result, where front-end checking systems are not capable of assuming the depth of our systems.

I use it whenever I make adjustments to configuration

(still learning how to use the forum)