Add IP-based SMTP authentication (#1149)

app/views/credentials/_form.html.haml

@@ -15,14 +15,23 @@
         %p.fieldSet__text
           This is a friendly name so you can identify this credential later. You can enter anything
           you want here, the more descriptive the better.
-    .fieldSet__field
+
+    .fieldSet__field{data: {credential_key_type: 'all'}}
       = f.label :key, :class => 'fieldSet__label'
       .fieldSet__input
-        = f.text_field :key, :readonly => true, :class => 'input input--text input--code', :placeholder => "Automatically generated", :tabindex => 1000, :value => (@credential.new_record? ? '' : @credential.key)
+        = f.text_field :key, :readonly => false, :class => 'input input--text input--code', :placeholder => "Automatically generated", :tabindex => 1000, :value => (@credential.new_record? ? '' : @credential.key)
         %p.fieldSet__text
-          This is the unique key which will be used to authenticate any requests to the API or our SMTP servers.
+          This is the unique key which will be used to authenticate any requests to the API or the SMTP servers.
           It will be generated randomly and cannot be changed. If you need a new token, you can create a new one and then
           delete the old one when you're ready.
+
+    .fieldSet__field{data: {credential_key_type: 'smtp-ip'}}
+      = f.label :key, "Network", :class => 'fieldSet__label'
+      .fieldSet__input
+        = f.text_field :key, :class => 'input input--text input--code'
+        %p.fieldSet__text
+          This is the IP address or network that you wish to allow to authenticate to this mail server.
+
     .fieldSet__field
       = f.label :hold, :class => 'fieldSet__label'
       .fieldSet__input