const listsubscriber = require('../../models').listsubscriber;

module.exports = (req, res) => {
  const unsubscribeKey = req.params.unsubscribeKey;

  listsubscriber.update(
    { subscribed: false },
    { where: { unsubscribeKey }}
  ).then(results => {
    // Redirect to a nicer unsubscribed page or similar
    // -- if results empty -> err
    res.status(200).send("successfully unsubscribed :(");
  });
}

@@ -370,20 +370,21 @@
 nd(%22
-successfully
+You have been
  uns
@@ -397,10 +397,31 @@
 bed 
-:(
+from this mailing list.
 %22);%0A

Modify unsubscription message