Support non-ASCII addresses (IDN)

.travis.yml

@@ -30,6 +30,9 @@ env:
 
 matrix:
   include:
+    - name: without-simpleidn
+      rvm: 2.5
+      env: SIMPLEIDN=no
     - name: actionmailer
       script: spec/travis-actionmailer.sh
       rvm: 2.5

Gemfile

@@ -26,6 +26,7 @@ elsif RUBY_VERSION < '2.2.2'
 end
 
 gem 'mini_mime'
+gem 'simpleidn' if RUBY_VERSION >= '1.9.3' && ENV['SIMPLEIDN'] != 'no'
 
 if RUBY_VERSION >= '2.0'
   gem 'byebug', :platforms => :mri

README.md

@@ -110,6 +110,10 @@ Installation is fairly simple, I host mail on rubygems, so you can just do:
 
     # gem install mail
 
+If you need support for email addresses with non-ASCII domains (IDNs), and your mail server lacks native support for these, you can install this additional optional dependency:
+
+    # gem install simpleidn
+
 ## Encodings
 
 If you didn't know, handling encodings in Emails is not as straight forward as you

lib/mail/elements/address.rb

@@ -71,6 +71,18 @@ def address(output_type = :decode)
       end
     end
 
+    # Returns the address that is in the address itself with domain IDNA-encoded.
+    #
+    #  a = Address.new('Mikel Lindsaar (My email address) <mikel@tést.lindsaar.net>')
+    #  a.address_idna #=> '[email protected]'
+    def address_idna
+      if d = domain_idna
+        "#{local}@#{d}"
+      else
+        local
+      end
+    end
+
     # Provides a way to assign an address to an already made Mail::Address object.
     #
     #  a = Address.new
@@ -120,6 +132,17 @@ def domain(output_type = :decode)
       Encodings.decode_encode(strip_all_comments(get_domain), output_type) if get_domain
     end
 
+    # Returns the domain part (the right hand side of the @ sign in the email address) of
+    # the address in IDNA encoding.
+    #
+    #  a = Address.new('Mikel Lindsaar (My email address) <mikel@tést.lindsaar.net>')
+    #  a.domain_idna #=> 'xn--tst-bma.lindsaar.net'
+    def domain_idna
+      if d = domain
+        Encodings.idna_encode(d)
+      end
+    end
+
     # Returns an array of comments that are in the email, or nil if there
     # are no comments
     #

lib/mail/encodings.rb

@@ -339,5 +339,22 @@ def Encodings.each_chunk_byterange(str, max_bytesize_per_chunk)
 
       yield RubyVer.string_byteslice(str, offset, chunksize)
     end
+
+    def Encodings.idna_supported?
+      begin
+        require 'simpleidn'
+        true
+      rescue LoadError => e
+        false
+      end
+    end
+
+    def Encodings.idna_encode(str)
+      return str if str.ascii_only?
+      raise 'Must install simpleidn gem' unless Encodings.idna_supported?
+
+      require 'simpleidn'
+      SimpleIDN.to_ascii(str)
+    end
   end
 end

lib/mail/smtp_envelope.rb

@@ -43,14 +43,18 @@ def message=(message)
 
     private
       def validate_addr(addr_name, addr)
-        if addr.bytesize > MAX_ADDRESS_BYTESIZE
-          raise ArgumentError, "SMTP #{addr_name} address may not exceed #{MAX_ADDRESS_BYTESIZE} bytes: #{addr.inspect}"
-        end
-
         if /[\r\n]/ =~ addr
           raise ArgumentError, "SMTP #{addr_name} address may not contain CR or LF line breaks: #{addr.inspect}"
         end
 
+        if !addr.ascii_only? && Encodings.idna_supported?
+          addr = Address.new(addr).address_idna
+        end
+
+        if addr.bytesize > MAX_ADDRESS_BYTESIZE
+          raise ArgumentError, "SMTP #{addr_name} address may not exceed #{MAX_ADDRESS_BYTESIZE} bytes: #{addr.inspect}"
+        end
+
         addr
       end
   end

spec/mail/elements/address_spec.rb

@@ -26,6 +26,12 @@
       end
     end
 
+    it "should allow us to instantiate an empty address object and call address_idna" do
+      [nil, '', ' '].each do |input|
+        expect(Mail::Address.new(input).address_idna).to be_nil
+      end
+    end
+
     it "should allow us to instantiate an empty address object and call local" do
       [nil, '', ' '].each do |input|
         expect(Mail::Address.new(input).local).to be_nil
@@ -38,6 +44,12 @@
       end
     end
 
+    it "should allow us to instantiate an empty address object and call domain_idna" do
+      [nil, '', ' '].each do |input|
+        expect(Mail::Address.new(input).domain_idna).to be_nil
+      end
+    end
+
     it "should allow us to instantiate an empty address object and call name" do
       [nil, '', ' '].each do |input|
         expect(Mail::Address.new(input).name).to be_nil
@@ -119,7 +131,18 @@
       expect(a.domain).to eq result
     end
 
-    it "should give back the formated address" do
+    it "should give back the IDNA-encoded domain" do
+      parse_text = 'Mikel Lindsaar <test@lindsäär.net>'
+      result     = 'xn--lindsr-fuaa.net'
+      a          = Mail::Address.new(parse_text)
+      if Mail::Encodings.idna_supported?
+        expect(a.domain_idna).to eq result
+      else
+        expect {a.domain_idna}.to raise_error("Must install simpleidn gem")
+      end
+    end
+
+    it "should give back the formatted address" do
       parse_text = 'Mikel Lindsaar <[email protected]>'
       result     = 'Mikel Lindsaar <[email protected]>'
       a          = Mail::Address.new(parse_text)

spec/mail/encodings_spec.rb

@@ -966,4 +966,24 @@ def convert(from, to)
       end
     end
   end
+
+  describe "IDNA encoding" do
+    it "should report on IDNA support" do
+      if RUBY_VERSION >= '1.9.3'
+        expect(Mail::Encodings.idna_supported?).to be true
+      else
+        expect(Mail::Encodings.idna_supported?).to be false
+      end
+    end
+
+    it "should encode a string correctly" do
+      raw = 'tést.example.com'
+      if Mail::Encodings.idna_supported?
+        encoded = 'xn--tst-bma.example.com'
+        expect(Mail::Encodings.idna_encode(raw)).to eq encoded
+      else
+        expect {Mail::Encodings.idna_encode(raw)}.to raise_error("Must install simpleidn gem")
+      end
+    end
+  end
 end

spec/mail/network/delivery_methods/smtp_spec.rb

@@ -262,6 +262,24 @@ def redefine_verify_none(new_value)
       expect(MockSMTP.deliveries[0][2]).to eq %w([email protected])
     end
 
+    it "IDNA-encodes non-ASCII From and To addresses" do
+      Mail.defaults do
+        delivery_method :smtp, :idna => true
+      end
+
+      Mail.deliver do
+        to "tö@soméemail.com"
+        from "fröm@soméemail.com"
+      end
+      if Mail::Encodings.idna_supported?
+        expect(MockSMTP.deliveries[0][1]).to eq 'frö[email protected]'
+        expect(MockSMTP.deliveries[0][2]).to eq %w(tö@xn--somemail-d1a.com)
+      else
+        expect(MockSMTP.deliveries[0][1]).to eq 'fröm@soméemail.com'
+        expect(MockSMTP.deliveries[0][2]).to eq %w(tö@soméemail.com)
+      end
+    end
+
     it "supports the null sender in the envelope from address" do
       Mail.deliver do
         to "[email protected]"