A bit of history to start off.

Years ago we started putting spf records in our domains and email clients domains and that is mostly where things stuck.
For the most part is was of little help but generally putting a correctly configured SPF statement did not hurt.

I recently discovered DMARC and decided to implement it on my own domain as an experiment.
After running for a while and looking at the information that came back from the other dmarcians I noticed some interesting trends.

1) Some days there are lots of spam messages sent to google as someone on my domain (likely me).
2) There are not a whole lot of people who are honouring dmarc and sending status messages.
3) Something in my network is sending mail to CheatCodes.com
Here is a snippet from my dmarc log.
Wed, 06 Jul 2016 14:47:25 -0400 CheatCodes.com 12
Thu, 07 Jul 2016 19:59:59 -0400 google.com 2
Thu, 07 Jul 2016 19:59:59 -0400 Yahoo! Inc. 2
Fri, 08 Jul 2016 11:29:47 -0400 CheatCodes.com 10
Sun, 10 Jul 2016 17:19:04 -0400 CheatCodes.com 3
Mon, 11 Jul 2016 19:59:59 -0400 google.com 2
Mon, 11 Jul 2016 14:45:57 -0400 CheatCodes.com 12
Tue, 12 Jul 2016 12:00:00 -0400 Microsoft Corp. 1
Tue, 12 Jul 2016 19:59:59 -0400 google.com 591
Tue, 12 Jul 2016 19:59:59 -0400 Yahoo! Inc. 8
Tue, 12 Jul 2016 15:22:56 -0400 CheatCodes.com 13
Wed, 13 Jul 2016 19:59:59 -0400 google.com 785
Wed, 13 Jul 2016 14:49:03 -0400 CheatCodes.com 3


So about cheatcodes.com.
All the traffic to cheatcodes is comming from the outside address of my firewall either home or cottage.
Since I only email via submission to my external mail-server there is nothing inside my domain that should be sending email.
So I blocked ports 25,2525 and a few other well known ports for email but still the mail is flowing.
Then I blocked the cheatcodes MX address class C... Still flowing.
I noticed that the IP source of the messages moved with my changing location.
There are only 3 connected things that will move between these locations. My laptop and 2 Android phones.
I guess its time to start more serious tracking of traffic from my portable devices.

So someone is connected and sending messages through non-regular channels to CheatCodes.com.
This disturbs me.
I intend to keep working on this.
But it makes me ask the question: Who would go so far as to setup a surreptitious email link and then run it through DMARC?

I have to admit that I kind of like DMARC.
It is letting me get a feel for  how much abuse of my domain is going on and it is way more than I thought.
Its by no means a spam solution but it can cut down spam generated in my name.


-- 
Alvin Starr                   ||   voice: (905)513-7688
Netvel Inc.                   ||   Cell:  (416)806-0133
alvin@netvel.net              ||