How to reject/detect emails claiming to be from my own domain?

Thom van der Boon thom at
Sat Dec 24 08:19:55 UTC 2016

I have more or less the same problem. I have a Mailscanner server which handles all mails from external sources, any internal mail is handled on a other server (which can not be reached from the Internet). This means that I can be pretty rude to any mail claiming to be from a local domain received from an external server on the MailScanner server 

I am currently testing the following setup: 

I added the file to /etc/mail/spamassassin with the following lines 

header __DSR_DOMAINCOM_VALID000 From =~ /\ 
header __DSR_DOMAINCOM_VALID001 To =~ /\ 
ifplugin Mail::SpamAssassin::Plugin::DKIM 
describe DSR_DOMAINCOM_VALID No valid mail 

Start testing with a lower score..... :) 

Met vriendelijke groet, Best regards, 

Thom van der Boon 
E-Mail: thom at 


Thom.H. van der Boon b.v. 
Transito 4 
6909 DA Babberich 
Tel.: +31 (0)88 4272727 
Fax: +31 (0)88 4272789 
Home Page: 

Van: "Philip Parsons" <pparsons at> 
Aan: "MailScanner Discussion" <mailscanner at> 
Verzonden: Vrijdag 23 december 2016 21:00:10 
Onderwerp: How to reject/detect emails claiming to be from my own domain? 

I use Mailscanner and Send mail. We have a few instances that we are receiving spam from jack at to jack at and it is getting through. I have not seemed to find and answers as to how to stop this? Anyone got an Idea. We already have SPF setup which helps but is not fully for this situation. 

Thank you. 
Philip Parsons 

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