app/views/door_mat/activity_mailer/confirm_email.html.erb
<p>To confirm your email, please visit the URL below</p>
<p>This email body is a DoorMat placeholder, override it with app/views/door_mat/activity_mailer/confirm_email.html.erb in your application.</p>
<ul>
<% @parameters.keys.each do |key| %>
<li>
<%= key %> -> <%= @parameters[key] %>
</li>
<% end %>
</ul>