Fix update mail templates

src/mail_templates/box_update_available.ejs

@@ -4,15 +4,18 @@ Dear <%= cloudronName %> Admin,
 
 Version <%= newBoxVersion %> for Cloudron <%= fqdn %> is now available!
 
-Your Cloudron will update automatically tonight. Alternately, update immediately at <%= webadminUrl %>.
-
 Changelog:
 <% for (var i = 0; i < changelog.length; i++) { %>
   * <%- changelog[i] %>
 <% } %>
 
-Thank you,
-your Cloudron
+<% if (!hasSubscription) { -%>
+*Keep your Cloudron automatically up-to-date and secure by upgrading to a paid plan at* <%= webadminUrl %>/#/settings
+<% } -%>
+
+Powered by https://cloudron.io
+
+Sent at: <%= new Date().toUTCString() %>
 
 <% } else { %>
 
@@ -27,11 +30,6 @@ your Cloudron
         Version <b><%= newBoxVersion %></b> for Cloudron <%= fqdn %> is now available!
     </p>
 
-    <p>
-        Your Cloudron will update automatically tonight.<br/>
-        Alternately, update immediately <a href="<%= webadminUrl %>">here</a>.
-    </p>
-
     <h5>Changelog:</h5>
     <ul>
     <% for (var i = 0; i < changelogHTML.length; i++) { %>
@@ -40,6 +38,11 @@ your Cloudron
     </ul>
 
     <br/>
+
+    <% if (!hasSubscription) { %>
+    <p>Keep your Cloudron automatically up-to-date and secure by upgrading to a <a href="<%= webadminUrl %>/#/settings">paid plan</a>.</p>
+    <% } %>
+
     <br/>
 </div>