2 files changed, 10 insertions, 1 deletions
diff --git a/actionmailer/lib/action_mailer/base.rb b/actionmailer/lib/action_mailer/base.rb
index 3a82979d35..9fb3ba425f 100644
--- a/actionmailer/lib/action_mailer/base.rb
+++ b/actionmailer/lib/action_mailer/base.rb
@@ -612,7 +612,11 @@ module ActionMailer #:nodoc:
       when user_content_type.present?
         user_content_type
       when m.has_attachments?
-        ["multipart", "mixed", params]
+        if m.attachments.detect { |a| a.inline? }
+          ["multipart", "related", params]
+        else
+          ["multipart", "mixed", params]
+        end
       when m.multipart?
         ["multipart", "alternative", params]
       else
diff --git a/actionmailer/lib/action_mailer/mail_helper.rb b/actionmailer/lib/action_mailer/mail_helper.rb
index aab6e12387..b708881edf 100644
--- a/actionmailer/lib/action_mailer/mail_helper.rb
+++ b/actionmailer/lib/action_mailer/mail_helper.rb
@@ -32,5 +32,10 @@ module ActionMailer
     def message
       @_message
     end
+
+    # Access the message attachments list.
+    def attachments
+      @_message.attachments
+    end
   end
 end