Add changelog/release note entries for missing ActionMailer super feature related to inclusion of callbacks in mailers

1 files changed, 2 insertions, 0 deletions

diff --git a/guides/source/4_0_release_notes.md b/guides/source/4_0_release_notes.md
index cce5bc5331..54fe49252f 100644
--- a/guides/source/4_0_release_notes.md
+++ b/guides/source/4_0_release_notes.md
@@ -141,6 +141,8 @@ Action Mailer
     end
     ```
 
+*   Allow for callbacks in mailers similar to ActionController::Base. You can now set up headers/attachments using `before_filter` or `after_filter`. You could also change delivery settings or prevent delivery in an after filter based on instance variables set in your mailer action. You have access to `ActionMailer::Base` instance methods like `message`, `attachments`, `headers`.
+
 Action Pack
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