I have this working:
You are aware that this "http:" leaves you open to various attacks that allow third parties to read your adminpw? If possible you should change this to https.
case $1 in 'add') curl "$H/add?subscribees=$2&adminpw=verysecret" ;; 'del') curl "$H/del?subscribees=$2&adminpw=verysecret" ;; esac
and scan the return for "Successfully [Un]subscribed"
Great! Thanks for the update.