diff --git a/defaults/main.yml b/defaults/main.yml
index 55d2072..7a71d80 100644
--- a/defaults/main.yml
+++ b/defaults/main.yml
@@ -21,7 +21,9 @@ certbot_dir: /opt/certbot
 # Set to true to have this role register and generate certificates for your
 # domains.
 certbot_handle_certs: true
-certbot_register_email: user@example.com
+
+# The email to register with (required).
+certbot_register_email: ''
 
 # The command to run to register with Let's Encrypt
 certbot_register_command: "{{ certbot_script }} register --non-interactive --agree-tos --email {{ certbot_register_email }}"
diff --git a/tasks/generate-certs.yml b/tasks/generate-certs.yml
index 78633c7..ff3a236 100644
--- a/tasks/generate-certs.yml
+++ b/tasks/generate-certs.yml
@@ -1,5 +1,11 @@
 ---
 
+- name: Make sure we have an email
+  assert:
+    that:
+    - "certbot_register_email is defined"
+    msg: "You need to provide an email address you own to register with Let's Encrypt."
+
 - name: Register with Let's Encrypt
   command: "{{ certbot_register_command }}"