Re: Avoid not authenticated forged mail

[Adrian Minta <gygy@stsnet.ro>]

Carlos Acedo wrote:
> Hi,
>
> Once in a while I receive spam "from my own" mail address, many users 
> send mails to themselfs, so what I would like is to allow only 
> authenticated mail to be able to send mails to themselfs. Is that 
> possible?
>
> Thank you in advance.
Create a file /etc/postfix/filters/sender_checks.pcre like this:
#check the From field
/^(.*)pangea\.org$/     550 please login first
/^(.*)smothersrealty\.com$/   554 known spammer domain

Edit smtpd_recipient_restrictions from /etc/postfix/main.cf  like this:
smtpd_recipient_restrictions =
   permit_mynetworks,
   permit_sasl_authenticated,
   reject_invalid_hostname,
   reject_non_fqdn_hostname,
   reject_non_fqdn_sender,
   reject_non_fqdn_recipient,
   reject_unknown_sender_domain,
   reject_unauth_destination,
   reject_unauth_pipelining,
#this is the LINE
   check_sender_access regexp:/etc/postfix/filters/sender_checks.pcre,
#RBL balcklists
   reject_rbl_client   zen.spamhaus.org

Also make sure that mynetworks is more restrictive.

--
Best regards,
Adrian Minta    MA3173-RIPE, MA314-ROTLD
tel. 0212.022.660 0726.110.369