Just installed the plugin so I'm testing everything.
From the dashboard,I unsuscribed all email addresses except one of mine. Then I "executed campaign" (for real, not a test).
I received the email and clicked the link "unsuscribe" and on the web page that opened from there, it's written "Unsubscription unsuccessful, try again!!!". And indeed on the email list, that email address still shows suscribed.
Can you help ?