diff --git a/content/html/content/src/nsHTMLInputElement.cpp b/content/html/content/src/nsHTMLInputElement.cpp
index 0c862a57b98..8110770129c 100644
--- a/content/html/content/src/nsHTMLInputElement.cpp
+++ b/content/html/content/src/nsHTMLInputElement.cpp
@@ -121,6 +121,8 @@
 #include "mozilla/LookAndFeel.h"
 #include "mozilla/Util.h" // DebugOnly
 
+#include "nsIIDNService.h"
+
 using namespace mozilla;
 using namespace mozilla::dom;
 
@@ -3918,18 +3920,34 @@ nsHTMLInputElement::IsValidEmailAddressList(const nsAString& aValue)
 bool
 nsHTMLInputElement::IsValidEmailAddress(const nsAString& aValue)
 {
+  nsCAutoString value = NS_ConvertUTF16toUTF8(aValue);
   PRUint32 i = 0;
-  PRUint32 length = aValue.Length();
+  PRUint32 length = value.Length();
+
+  // Puny-encode the string if needed before running the validation algorithm.
+  nsCOMPtr<nsIIDNService> idnSrv = do_GetService(NS_IDNSERVICE_CONTRACTID);
+  if (idnSrv) {
+    bool ace;
+    if (NS_SUCCEEDED(idnSrv->IsACE(value, &ace)) && !ace) {
+      nsCAutoString punyCodedValue;
+      if (NS_SUCCEEDED(idnSrv->ConvertUTF8toACE(value, punyCodedValue))) {
+        value = punyCodedValue;
+        length = value.Length();
+      }
+    }
+  } else {
+    NS_ERROR("nsIIDNService isn't present!");
+  }
 
   // If the email address is empty, begins with a '@' or ends with a '.',
   // we know it's invalid.
-  if (length == 0 || aValue[0] == '@' || aValue[length-1] == '.') {
+  if (length == 0 || value[0] == '@' || value[length-1] == '.') {
     return false;
   }
 
   // Parsing the username.
-  for (; i < length && aValue[i] != '@'; ++i) {
-    PRUnichar c = aValue[i];
+  for (; i < length && value[i] != '@'; ++i) {
+    PRUnichar c = value[i];
 
     // The username characters have to be in this list to be valid.
     if (!(nsCRT::IsAsciiAlpha(c) || nsCRT::IsAsciiDigit(c) ||
@@ -3948,17 +3966,17 @@ nsHTMLInputElement::IsValidEmailAddress(const nsAString& aValue)
   }
 
   // The domain name can't begin with a dot.
-  if (aValue[i] == '.') {
+  if (value[i] == '.') {
     return false;
   }
 
   // Parsing the domain name.
   for (; i < length; ++i) {
-    PRUnichar c = aValue[i];
+    PRUnichar c = value[i];
 
     if (c == '.') {
       // A dot can't follow a dot.
-      if (aValue[i-1] == '.') {
+      if (value[i-1] == '.') {
         return false;
       }
     } else if (!(nsCRT::IsAsciiAlpha(c) || nsCRT::IsAsciiDigit(c) ||
diff --git a/content/html/content/test/forms/test_input_email.html b/content/html/content/test/forms/test_input_email.html
index 8b2b2fe7bd4..e6d16d4f0b3 100644
--- a/content/html/content/test/forms/test_input_email.html
+++ b/content/html/content/test/forms/test_input_email.html
@@ -87,6 +87,7 @@ var values = [
   [ 'f\noo@bar.com', true ],
   [ 'f\roo@bar.com', true ],
   [ 'f\r\noo@bar.com', true ],
+  [ 'fü@foo.com', true ],
   // Some checks for the domain part.
   [ 'foo@bar', true ],
   [ 'foo@b', true ],
@@ -104,6 +105,11 @@ var values = [
   [ 'foo@b\rar.com', true ],
   [ 'foo@b\r\nar.com', true ],
   [ 'foo@.', false ],
+  [ 'foo@fü.com', true ],
+  [ 'foo@fu.cüm', true ],
+  // Long strings with UTF-8.
+  [ 'this.is.email.should.be.longer.than.sixty.four.characters.föö@mözillä.tld', true ],
+  [ 'this-is-email-should-be-longer-than-sixty-four-characters-föö@mözillä.tld', true, true ],
 ];
 
 // Multiple values, we don't check e-mail validity, only multiple stuff.
@@ -170,8 +176,13 @@ for each (c in illegalCharacters) {
   values.push(['foo@foo.ba' + c + 'r', false]);
 }
 
-values.forEach(function([value, valid]) {
-  testEmailAddress(email, value, false, valid);
+values.forEach(function([value, valid, todo]) {
+  if (todo === true) {
+    email.value = value;
+    todo_is(email.validity.valid, true, "value should be valid");
+  } else {
+    testEmailAddress(email, value, false, valid);
+  }
 });
 
 multipleValues.forEach(function([value, valid]) {
diff --git a/content/html/content/test/test_formSubmission.html b/content/html/content/test/test_formSubmission.html
index db7dfdac2b0..a5a0a17c9a7 100644
--- a/content/html/content/test/test_formSubmission.html
+++ b/content/html/content/test/test_formSubmission.html
@@ -240,6 +240,19 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=523771
           <!-- Put UTF-8 value in the "strange" column. -->
           <input type=url name="n19_8" value="http://m&#xf3;zill&auml;.&#xf3;rg"></td>
     </tr>
+    <tr>
+      <td>&lt;input type='email'&gt;</td>
+      <td><input type=email name="n20_1" value="v20_1@bar"></td>
+      <td><input type=email name="n20_2" value=""></td>
+      <td><input type=email name="n20_3"></td>
+      <td><input type=email name="" value="v20_4@bar"></td>
+      <td><input type=email value="v20_5@bar"></td>
+      <td><input type=email ></td>
+      <td><input type=email name="n20_7_&#13;_&#10;_&#13;&#10;__&quot;"
+                 value="v20_7_&#13;_&#10;_&#13;&#10;__&quot;@bar">
+          <!-- Put UTF-8 value is the "strange" column. -->
+          <input type=email name="n20_8" value="foo@mózillä.órg"></td>
+    </tr>
   </table>
   
   <p>
@@ -472,6 +485,12 @@ var expectedSub = [
   { name: "n19_3", value: "" },
   { name: "n19_7_\r\n_\r\n_\r\n__\"", value: "http://v19_7_____\"" },
   { name: "n19_8", value: "http://m\xf3zill\xe4.\xf3rg" },
+  // <input type='email'>
+  { name: "n20_1", value: "v20_1@bar" },
+  { name: "n20_2", value: "" },
+  { name: "n20_3", value: "" },
+  { name: "n20_7_\r\n_\r\n_\r\n__\"", value: "v20_7_____\"@bar" },
+  { name: "n20_8", value: "foo@mózillä.órg" },
   // Default button
   // Submit button
   // Button button
@@ -612,7 +631,8 @@ function utf8encode(s) {
 function checkURLSubmission(sub, expected) {
   function urlEscape(s) {
     return escape(utf8encode(s)).replace("%20", "+", "g")
-                                .replace("/", "%2F", "g");
+                                .replace("/", "%2F", "g")
+                                .replace("@", "%40", "g");
   }
 
   subItems = sub.split("&");