How to configure Postfix to allow incoming mails only from one defined mail-id

To accomplish this, add the following smtpd_sender_restrictions to your main.cf to receive email only from my@domain.com:

#/etc/postfix/main.cf
smtpd_sender_restrictions = check_sender_access regexp:/etc/postfix/mine_only

#/etc/postfix/mine_only
/^my@domain.com$/   OK
/^/                 REJECT