hi there, I'm running postfix with several header_checks that appear to be being ignored. eg; I don't see anything in the mail.log relating to the entries which should be found (and rejected). This may be something obvious (it usually is), but I'm scratching my head here. Here's a snippet of email header that I'm trying to block, which is still getting through: Code: Return-Path: <[email protected]> This is part of the header_checks file, entered via the ISPConfig3 email content filter interface: Code: # cat /etc/postfix/header_checks /^Return-Path: .*(?=rfi\[email protected]\.).*/ REJECT spam_40 /(GB2312|koi-r|iso-2022-jp)/ REJECT spam_12 /^((To|Cc|From):.*@(icq|qq)\.)/ REJECT spam_45 This file is referenced in postfix's main.cf: Code: # grep header_checks /etc/postfix/main.cf header_checks = regexp:/etc/postfix/header_checks mime_header_checks = regexp:/etc/postfix/mime_header_checks nested_header_checks = regexp:/etc/postfix/nested_header_checks I've reloaded and restarted postfix several times, here is the current postfix status: Code: # systemctl status postfix ● postfix.service - Postfix Mail Transport Agent Loaded: loaded (/lib/systemd/system/postfix.service; enabled; vendor preset: enabled) Active: active (exited) since Sat 2021-06-05 18:48:20 UTC; 5min ago Process: 17009 ExecStart=/bin/true (code=exited, status=0/SUCCESS) Main PID: 17009 (code=exited, status=0/SUCCESS) Jun 05 18:48:20 mythic.rfi.net systemd: Starting Postfix Mail Transport Agent... Jun 05 18:48:20 mythic.rfi.net systemd: Started Postfix Mail Transport Agent. This is the relevant log file entry - empty - where I'd expect to see a REJECT for the above email header: Code: # grep spam_ /var/log/mail.log # I have ISPConfig3 3.2.4 running on a Debian Buster Linux mythic.rfi.net 4.19.0-8-686-pae #1 SMP Debian 4.19.98-1+deb10u1 (2020-04-27) i686 GNU/Linux I'd be keen to hear any helpful suggestions. Many thanks in advance.