==== Required information ====
CentOS Linux release 7.3.1611 (Core)
Apache 2.4.6
iRedMail    v0.9.6
iRedAdmin-Pro     v2.6.0 (MySQL)
====

I'm at wit's end...
SUMMARY:
Off server relayed emails fail with "Policy rejection not logged in" when Reply_Path header is iredmail alias email address.

EXCRUCIATING DETAILS:
Sending server is in iredmail's postfix main.cf mynetworks list.
/opt/iredapd/settings.py contains
    ALLOWED_FORGED_SENDERS = ["AliasAddr@iredmail-hosted-domain.com"]

THIS DOES *NOT* FAIL:
$hdrs  = array(
              'From'    => 'AliasAddr@iredmail-hosted-domain.com',
              'Subject' => 'Test message'
              );

amavis[12345]: (12345-11) Passed CLEAN {RelayedInternal}, MYNETS LOCAL [10.240.0.6]:46468 <anonymous@mynetwoks.listed.host> -> <me@gmail.com>, Queue-ID: 305FE98E7D, Message-ID: <20170410165114.22667.qmail@mynetwoks.listed.host>, mail_id: cp8783wu13uJ, Hits: -0.998, size: 980, queued_as: 64B64971ED, 196 ms, Tests: [ALL_TRUSTED=-1,HEADER_FROM_DIFFERENT_DOMAINS=0.001,HTML_MESSAGE=0.001]

THIS FAILS:
$hdrs  = array(
              'From'    => 'AliasAddr@iredmail-hosted-domain.com',
              'Return-Path' => 'AliasAddr@iredmail-hosted-domain.com',
              'Subject' => 'Test message'
              );

554 5.7.1 <me@gmail.com>: Recipient address rejected: Policy rejection not logged in; from=<AliasAddr@iredmail-hosted-domain.com> to=<me@gmail.com> proto=ESMTP helo=<mynetwoks.listed.host>

I sure would like to get this working because I have been haranguing my clients for month's to update their web site email sending programs to specify an appropriate Reply_Path header.

tia
dave