Create the custom template dir:
mkdir -p /etc/e-smith/templates-custom/etc/postfix/main.cf
Edit the custom template, I use nano
nano /etc/e-smith/templates-custom/etc/postfix/main.cf/90recp_limit
Write the following in the custom template and save it:
default_recipient_limit = 100
Expand the template:
expand-template /etc/postfix/main.cf
Restart postfix:
systemctl restart postfix