http://guides.thnic.or.th/eai-setup-guidelines/index.php/Main_Page
EAI filter for postfix
This filter check for the receiving mail server if it supports SMTPUTF8, if it does not support it will rewrite the FROM Address with ASCII only that is aliased to the sender email.
Copy eaifilter.php in /etc/postfix Change to root
smtp inet n - n - - smtpd -o content_filter=eaifilter -o receive_override_options=no_header_body_checks
eaifilter unix - n n - - pipe flags=RXhu user=nobody argv=/etc/postfix/eaifilter.php -f ${sender} -d ${recipient}
127.0.0.1:10025 inet n - n - - smtpd
-o content_filter=
-o receive_override_options=no_unknown_recipient_checks,no_header_body_checks,no_milters
-o smtpd_helo_required=no
-o smtpd_helo_restrictions=
-o smtpd_data_restrictions=
-o smtpd_client_restrictions=
-o smtpd_sender_restrictions=
-o smtpd_recipient_restrictions=permit_mynetworks,reject
-o mynetworks_style=host
-o in_flow_delay=0
eaifilter_destination_recipient_limit=1