sender from [email protected]

I received some spams per day from xyz or someone random @mydomain.com! e.g. I got a valid user [email protected] but this account will receive email from [email protected] but which william is not a valid account in ispconfig.

I also tried to telnet mail.abc.com. Whatever I entered "mail from: [email protected]" if the recipient is the valid one, postfix will pass it.

I know that it's really hard to check the sender mail address valid, but is there any solution to restrict the sender if it's the same domain as in database?

in main.cf, add something in smtpd_sender_restrictions or smtpd_recipient_restrictions ?

Before use ispconfig, my main.cf is,

Code:

smtpd_recipient_restrictions =
        permit_mynetworks,
        permit_sasl_authenticated,
        reject_non_fqdn_hostname,
        reject_non_fqdn_sender,
        reject_non_fqdn_recipient,
        reject_unauth_destination,
        reject_unauth_pipelining,
        reject_invalid_hostname,
        check_policy_service inet:127.0.0.1:10030