I'm running Zimbra 8.6 Network Edition and I'm trying to prevent compromised mailboxes on my platform from spoofing other domains on the same platform.

I've enforced reject_sender_login_mismatch in the Postfix configs as shown below.

smtpd_sender_restrictions = reject_authenticated_sender_login_mismatch, check_sender_access regexp:/opt/zimbra/postfix/conf/tag_as_originating.re, reject_sender_login_mismatch, permit_sasl_authenticated, permit_tls_clientcerts, check_sender_access regexp:/opt/zimbra/postfix/conf/tag_as_foreign.re

Telnet tests are showing that spoofing is being blocked as required but on Microsoft Outlook and Thunderbird it seems spoofed From addresses are being embedded in IMF messages to circumvent the checks.

Is there a way I can get Postfix to do IMF message checks and reject the email if the IMF From is different from the Auth'ed user's address?

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