Creating filter which sends error mails back

Question

In the next year I want to set up a personal email server with custom domain etc.

For spam issues, I want to create an email filter which sends in case of spam the exact same message back, like it would be, if the address wouldn't exist. This way, the spammers can not tell if it is a filter or the address doesn't exist.

Is there an existing solution, which supports this or supports tools to create this?

I haven't found anything yet.

Answer 1

You have many solution for this, if you use postfix you could use:

• Postgrey
• Spamassassin

and you could also enable smtpd_client_restrictions in posfix by adding a rule to reject_rbl_client. For example in your master.cf file:

smtpd_recipient_restrictions =
        permit_mynetworks,
        permit_sasl_authenticated,
        reject_unauth_destination
        reject_unauth_pipelining,
        reject_unknown_reverse_client_hostname,
        reject_invalid_helo_hostname,
        reject_non_fqdn_helo_hostname,
        reject_non_fqdn_sender,
        reject_non_fqdn_recipient,
        reject_unknown_sender_domain,
        reject_unknown_recipient_domain,
        reject_invalid_hostname,
        reject_rbl_client zen.spamhaus.org,
        reject_rbl_client bl.spamcop.net,
        reject_rbl_client b.barracudacentral.org,
        reject_rbl_client dnsbl.sorbs.net,
        permit