diff --git a/actionmailer/lib/action_mailer/base.rb b/actionmailer/lib/action_mailer/base.rb
index 000c05d19bf3..84997de3ceb5 100644
--- a/actionmailer/lib/action_mailer/base.rb
+++ b/actionmailer/lib/action_mailer/base.rb
@@ -543,6 +543,7 @@ def initialize_defaults(method_name)
         @headers ||= {}
         @body ||= {}
         @mime_version = @@default_mime_version.dup if @@default_mime_version
+        @sent_on ||= Time.now
       end
 
       def render_message(method_name, body)
diff --git a/actionmailer/test/mail_service_test.rb b/actionmailer/test/mail_service_test.rb
index 277a91395db7..3244aad24902 100644
--- a/actionmailer/test/mail_service_test.rb
+++ b/actionmailer/test/mail_service_test.rb
@@ -18,7 +18,6 @@ def signed_up(recipient)
     @recipients   = recipient
     @subject      = "[Signed up] Welcome #{recipient}"
     @from         = "system@loudthinking.com"
-    @sent_on      = Time.local(2004, 12, 12)
     @body["recipient"] = recipient
   end
 
@@ -356,12 +355,14 @@ def test_attachment_with_custom_header
   end
 
   def test_signed_up
+    Time.stubs(:now => Time.now)
+
     expected = new_mail
     expected.to      = @recipient
     expected.subject = "[Signed up] Welcome #{@recipient}"
     expected.body    = "Hello there, \n\nMr. #{@recipient}"
     expected.from    = "system@loudthinking.com"
-    expected.date    = Time.local(2004, 12, 12)
+    expected.date    = Time.now
 
     created = nil
     assert_nothing_raised { created = TestMailer.create_signed_up(@recipient) }