I'm trying to apply this answer to my zimbra installation as I'm getting a postmaster email every time I send an encrypted email.
I tried adding
$admin_maps_by_ccat{+CC_UNCHECKED} = undef;
to /opt/zimbra/conf/amavisd.conf and zmamavisdctl stop; zmamavisdctl start
but it just removes the directive from the configuration file.
Any assistance greatly appreciated!