Look into SPF.
...Kevin -- Kevin Miller Network/email Administrator, CBJ MIS Dept. 155 South Seward Street Juneau, Alaska 99801 Phone: (907) 586-0242, Fax: (907) 586-4588 Registered Linux User No: 307357 From: owner-postfix-us...@postfix.org [mailto:owner-postfix-us...@postfix.org] On Behalf Of John Baker Sent: Wednesday, March 30, 2016 10:46 AM To: postfix-users Subject: best practice for blocking fake local domain senders We've gone a long time without specifically needing this but suddenly we are getting bombarded with spam pretending to be from one of our addresses but originating from outside. So I need to block mail with a @marlboro.edu<http://marlboro.edu> sender unless it helos from local servers or specific external IP ranges. I have a few ideas on how to do this but but wondered if anybody could quickly point me in the direction of best practices for this. Is there a simple way or is it best to use smtpd_restriction_classes? thanks -- John Baker Network Administrator Marlboro College Phone: 451-7551 Cell: 490-0066
