7 files changed, 25 insertions, 7 deletions
diff --git a/actionmailer/README.rdoc b/actionmailer/README.rdoc
index 74d7ea65ce..0db4b2668b 100644
--- a/actionmailer/README.rdoc
+++ b/actionmailer/README.rdoc
@@ -13,6 +13,8 @@ Additionally, an Action Mailer class can be used to process incoming email,
 such as allowing a blog to accept new posts from an email (which could even
 have been sent from a phone).
 
+You can read more about Action Mailer in the {Action Mailer Basics}[https://edgeguides.rubyonrails.org/action_mailer_basics.html] guide.
+
 == Sending emails
 
 The framework works by initializing any instance variables you want to be
@@ -128,7 +130,7 @@ Action Mailer is released under the MIT license:
 
 API documentation is at
 
-* http://api.rubyonrails.org
+* https://api.rubyonrails.org
 
 Bug reports for the Ruby on Rails project can be filed here:
 
diff --git a/actionmailer/actionmailer.gemspec b/actionmailer/actionmailer.gemspec
index c76cb3ec72..cadccb905b 100644
--- a/actionmailer/actionmailer.gemspec
+++ b/actionmailer/actionmailer.gemspec
@@ -15,7 +15,7 @@ Gem::Specification.new do |s|
 
   s.author   = "David Heinemeier Hansson"
   s.email    = "david@loudthinking.com"
-  s.homepage = "http://rubyonrails.org"
+  s.homepage = "https://rubyonrails.org"
 
   s.files        = Dir["CHANGELOG.md", "README.rdoc", "MIT-LICENSE", "lib/**/*"]
   s.require_path = "lib"
diff --git a/actionmailer/lib/action_mailer/base.rb b/actionmailer/lib/action_mailer/base.rb
index 52360d40fe..c1ac9c2ad1 100644
--- a/actionmailer/lib/action_mailer/base.rb
+++ b/actionmailer/lib/action_mailer/base.rb
@@ -944,9 +944,9 @@ module ActionMailer
         assignable.each { |k, v| message[k] = v }
       end
 
-      def collect_responses(headers)
+      def collect_responses(headers, &block)
         if block_given?
-          collect_responses_from_block(headers, &Proc.new)
+          collect_responses_from_block(headers, &block)
         elsif headers[:body]
           collect_responses_from_text(headers)
         else
@@ -973,10 +973,10 @@ module ActionMailer
         templates_name = headers[:template_name] || action_name
 
         each_template(Array(templates_path), templates_name).map do |template|
-          self.formats = [template.format]
+          format = template.format || self.formats.first
           {
-            body: render(template: template),
-            content_type: template.type.to_s
+            body: render(template: template, formats: [format]),
+            content_type: Mime[format].to_s
           }
         end
       end
diff --git a/actionmailer/test/base_test.rb b/actionmailer/test/base_test.rb
index 531bf58ea9..c07fca5b5e 100644
--- a/actionmailer/test/base_test.rb
+++ b/actionmailer/test/base_test.rb
@@ -307,6 +307,16 @@ class BaseTest < ActiveSupport::TestCase
     assert_equal("HTML Implicit Multipart", email.parts[1].body.encoded)
   end
 
+  test "implicit multipart formats" do
+    email = BaseMailer.implicit_multipart_formats
+    assert_equal(2, email.parts.size)
+    assert_equal("multipart/alternative", email.mime_type)
+    assert_equal("text/plain", email.parts[0].mime_type)
+    assert_equal("Implicit Multipart [:text]", email.parts[0].body.encoded)
+    assert_equal("text/html", email.parts[1].mime_type)
+    assert_equal("Implicit Multipart [:html]", email.parts[1].body.encoded)
+  end
+
   test "implicit multipart with sort order" do
     order = ["text/html", "text/plain"]
     with_default BaseMailer, parts_order: order do
diff --git a/actionmailer/test/fixtures/base_mailer/implicit_multipart_formats.html.erb b/actionmailer/test/fixtures/base_mailer/implicit_multipart_formats.html.erb
new file mode 100644
index 0000000000..0179b070b8
--- /dev/null
+++ b/actionmailer/test/fixtures/base_mailer/implicit_multipart_formats.html.erb
@@ -0,0 +1 @@
+Implicit Multipart <%= formats.inspect %>
+\ No newline at end of file
diff --git a/actionmailer/test/fixtures/base_mailer/implicit_multipart_formats.text.erb b/actionmailer/test/fixtures/base_mailer/implicit_multipart_formats.text.erb
new file mode 100644
index 0000000000..0179b070b8
--- /dev/null
+++ b/actionmailer/test/fixtures/base_mailer/implicit_multipart_formats.text.erb
@@ -0,0 +1 @@
+Implicit Multipart <%= formats.inspect %>
+\ No newline at end of file
diff --git a/actionmailer/test/mailers/base_mailer.rb b/actionmailer/test/mailers/base_mailer.rb
index dbe1c4f0e6..6bd58304e2 100644
--- a/actionmailer/test/mailers/base_mailer.rb
+++ b/actionmailer/test/mailers/base_mailer.rb
@@ -62,6 +62,10 @@ class BaseMailer < ActionMailer::Base
     mail(hash)
   end
 
+  def implicit_multipart_formats(hash = {})
+    mail(hash)
+  end
+
   def implicit_with_locale(hash = {})
     mail(hash)
   end