/var/qmail/control/badmailfrom is definitely templated, so you should move your customizations to a template fragment.
Basically, this means creating a file containing your desired content in a folder named /etc/e-smith/templates-custom/var/qmail/control/badmailfrom, something like this:mkdir -p /etc/e-smith/templates-custom/var/qmail/control/badmailfrom
pico -w /etc/e-smith/templates-custom/var/qmail/control/badmailfrom/20badmailfrom
Add the email addresses you want to block to 20badmailfrom, one per line. When done, save your changes and do:expand-template /var/qmail/control/badmailfrom
signal-event email-update
The SME templating system will look at /etc/e-smith/templates and /etc/e-smith/templates-custom and process any template fragments found for a particular file (/var/qmail/control/badmailfrom, in our example) alphabetically. If there are identically named fragments in .../templates/... and in .../templates-custom/..., the custom version will be used and the non-custom version will be ignored.