Spoofing Problem

admin admin at tsys3.com
Tue Jul 9 16:58:22 UTC 2019

Good Afternoon,

I have my mailscanner setup as a gateway.  I use postfix in my setup and 
have done the following to prevent spoofing going to my domain users.

in main.cf I put the following
smtpd_recipient_restrictions = reject_unauth_destination, 
check_recipient_access hash:/etc/postfix/spoofingprotected_domains

Add your domain to the spoofingprotected_domains.  So far this has 
worked for me.

On 07/09/19 12:38 PM, Bilal via MailScanner wrote:
> I am facing a problem that someone is spoofing my domain address and 
> sending emails to my own domain users.  I have set valid SPF, DKIM, 
> DMARC for my Mail server.
> To sort this problem I have filter emails based on SPF checks and the 
> email with spf fail are marked high score and marked as spam. But the 
> issue with spf filter many legitimate email from many servers marked 
> as spam.
> More importantly my own emails spf fails shown in MailScanner while I 
> have verified through Gmail and various other tools that my SPF , 
> DKIM, DMARC are passed.
> My Mail server is hosted inside in private network and NAT behind the 
> public DNS , since in public DNS I have spf according to mail server 
> public interface so in local intranet DNS I added SPF records 
> according to email server private ip,
> Now few time spf shown as pass in mailscanner and mostly fail . 
> Temporarily I have whitelisted my server host ip and my intranet ip to 
> avoid email blocking due to spf fail . Please someone guide any 
> solution to either I can stop email spoofing to my domain without spf 
> check or otherwise how can I sort this spf fail issue on mailscanner .
> this also block many legitimate email with spf not set properly
> *Bilal Ahmad*
> Network Administrator
> Cell: +92 333 7451870 |  Tel: +92 68 5882400 |  Ext. 2499
> www.kfueit.edu.pk
> <http://www.kfueit.edu.pk/>
> -- 
> This message has been scanned for viruses and
> dangerous content by *MailScanner* <http://www.mailscanner.info/>, and is
> believed to be clean.

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