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diff --git a/guides/source/i18n.md b/guides/source/i18n.md
index c1b575c7b7..8340d6807f 100644
--- a/guides/source/i18n.md
+++ b/guides/source/i18n.md
@@ -712,6 +712,19 @@ en:
 
 Then `User.model_name.human(count: 2)` will return "Dudes". With `count: 1` or without params will return "Dude".
 
+In the event you need to access nested attributes within a given model, you should nest these under `model/attribute` at the model level of your translation file:
+
+```yaml
+en:
+  activerecord:
+    attributes:
+      user/gender:
+        female: "Female"
+        male: "Male"
+```
+
+Then `User.human_attribute_name("gender.female")` will return "Female".
+
 #### Error Message Scopes
 
 Active Record validation error messages can also be translated easily. Active Record gives you a couple of namespaces where you can place your message translations in order to provide different messages and translation for certain models, attributes, and/or validations. It also transparently takes single table inheritance into account.
@@ -847,6 +860,24 @@ en:
       subject: "Welcome to Rails Guides!"
 ```
 
+To send parameters to interpolation use the `default_i18n_subject` method on the mailer.
+
+```ruby
+# user_mailer.rb
+class UserMailer < ActionMailer::Base
+  def welcome(user)
+    mail(to: user.email, subject: default_i18n_subject(user: user.name))
+  end
+end
+```
+
+```yaml
+en:
+  user_mailer:
+    welcome:
+      subject: "%{user}, welcome to Rails Guides!"
+```
+
 ### Overview of Other Built-In Methods that Provide I18n Support
 
 Rails uses fixed strings and other localizations, such as format strings and other format information in a couple of helpers. Here's a brief overview.