How to Remove UNCHECKED Term Attached in Email Subject Area When Received

You can use the parameter %admin_maps_by_ccat to define whom amavisd-new sends Mails for each of its categories. With undef you can disable the mails.

So you have to define a setting like the following if you don't want to get mails for all "unchecked" mails:

$admin_maps_by_ccat{+CC_UNCHECKED} =  undef;

To only do this for UNCHECKED-ENCRYPTED use this (for amavis 2.9.0, found via release notes):

$admin_maps_by_ccat{+CC_UNCHECKED.',1'} = undef;