app/views/notifier/send_create_user_email.html.erb
<h1>Hello!!</h1>
You have been invited to join <b>WatchIoT</b>.
<a href="<%= url_for(controller: 'notifications', action: 'invite', token: @token, only_path: false) %>">Click here to activate</a> your <b>WatchIoT</b> account
<br/><br/>
WatchIoT Support